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| Mendeliome v1.1959 | ELMOD3 | Zornitza Stark edited their review of gene: ELMOD3: Added comment: Discussed at GenCC: limited.; Changed rating: RED | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mendeliome v1.1840 | PRRX1 |
Melanie Marty changed review comment from: > 17 individuals with Craniosynostosis from 14 families had been found to have rare heterozygous variants in PRRX1, loss of function variants (PTCs, start loss and partial/full gene del) or missense variants affecting the homeodomain. > These consisted of three de novo variants, but for the majority of cases the variant was inherited from an unaffected parent, yielding an estimate for the penetrance of craniosynostosis of 12.5%. > These results were also supported by immunofluorescence analyses which showed that missense variants within the PRRX1 homeodomain cause abnormal nuclear localisation (PMID: 37154149) > Authors discuss how the previous reports of agnathia-otocephaly doesn't fit with this new evidence and they showed that a missense variant previously reported in a patient with agnathia-otocephaly p.(Phe113Leu) did not affect nuclear import. Supporting evidence: > Post-natal calvarial stem cells expressing Prrx1 have been shown to reside exclusively in the calvarial suture niche, suggesting a requirement for PRRX1 regarding suture patency during early development (PMID: 28366454) >Prrx1 has been shown to be widely expressed within the mouse coronal suture (PMID: 34376651) >Agnathia-otocephaly complex, 2 x missense variants (1 x het, 1 x hom) and 2 x frameshifts reported (het). The frameshift variants both occur in a poly A tract (PMID: 21294718, PMID: 22674740, PMID: 23444262, PMID: 22211708). Authors of the more recent publication on Craniosynostosis (PMID: 37154149) cast some doubt on the reports for Agnathia-otocephaly, possible explanations discussed are that this condition is AR and a 2nd hit was missed or another cause was not identified such as variants in OTX2. > PMID: 7758948 generated a loss-of-function mutation in the mouse Pmx1 gene. Mice homozygous for the mutant allele died soon after birth and exhibited defects of skeletogenesis, which involved the loss or malformation of craniofacial, limb, and vertebral skeletal structures. ; to: Craniosynostosis (MONDO:0015469), PRRX1-related > 17 individuals with Craniosynostosis from 14 families had been found to have rare heterozygous variants in PRRX1, loss of function variants (PTCs, start loss and partial/full gene del) or missense variants affecting the homeodomain. > These consisted of three de novo variants, but for the majority of cases the variant was inherited from an unaffected parent, yielding an estimate for the penetrance of craniosynostosis of 12.5%. > These results were also supported by immunofluorescence analyses which showed that missense variants within the PRRX1 homeodomain cause abnormal nuclear localisation (PMID: 37154149) > Authors discuss how the previous reports of agnathia-otocephaly doesn't fit with this new evidence and they showed that a missense variant previously reported in a patient with agnathia-otocephaly p.(Phe113Leu) did not affect nuclear import. Supporting evidence: > Post-natal calvarial stem cells expressing Prrx1 have been shown to reside exclusively in the calvarial suture niche, suggesting a requirement for PRRX1 regarding suture patency during early development (PMID: 28366454) >Prrx1 has been shown to be widely expressed within the mouse coronal suture (PMID: 34376651) Agnathia-otocephaly complex, MIM# 202650 >Agnathia-otocephaly complex, 2 x missense variants (1 x het, 1 x hom) and 2 x frameshifts reported (het). The frameshift variants both occur in a poly A tract (PMID: 21294718, PMID: 22674740, PMID: 23444262, PMID: 22211708). Authors of the more recent publication on Craniosynostosis (PMID: 37154149) cast some doubt on the reports for Agnathia-otocephaly, possible explanations discussed are that this condition is AR and a 2nd hit was missed or another cause was not identified such as variants in OTX2. > PMID: 7758948 generated a loss-of-function mutation in the mouse Pmx1 gene. Mice homozygous for the mutant allele died soon after birth and exhibited defects of skeletogenesis, which involved the loss or malformation of craniofacial, limb, and vertebral skeletal structures. |
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| Mendeliome v1.1840 | PRRX1 |
Melanie Marty changed review comment from: > 17 individuals with Craniosynostosis from 14 families had been found to have rare heterozygous variants in PRRX1, loss of function variants (PTCs, start loss and partial/full gene del) or missense variants affecting the homeodomain. > These consisted of three de novo variants, but for the majority of cases the variant was inherited from an unaffected parent, yielding an estimate for the penetrance of craniosynostosis of 12.5%. > These results were also supported by immunofluorescence analyses which showed that missense variants within the PRRX1 homeodomain cause abnormal nuclear localisation (PMID: 37154149) > Authors discuss how the previous reports of agnathia-otocephaly doesn't fit with this new evidence and they showed that a missense variant previously reported in a patient with agnathia-otocephaly p.(Phe113Leu) did not affect nuclear import. Supporting evidence: > Post-natal calvarial stem cells expressing Prrx1 have been shown to reside exclusively in the calvarial suture niche, suggesting a requirement for PRRX1 regarding suture patency during early development (PMID: 28366454) >Prrx1 has been shown to be widely expressed within the mouse coronal suture (PMID: 34376651) >Agnathia-otocephaly complex, 2 x missense variants (1 x het, 1 x hom) and 2 x frameshifts reported (het). The frameshift variants both occur in a poly A tract (PMID: 21294718, PMID: 22674740, PMID: 23444262, PMID: 22211708). Authors of the more recent publication on Craniosynostosis (PMID: 37154149) cast some doubt on the reports for Agnathia-otocephaly, possible explanations discussed are that this condition is AR and a 2nd hit was missed or another cause was not identified such as variants in OTX2.; to: > 17 individuals with Craniosynostosis from 14 families had been found to have rare heterozygous variants in PRRX1, loss of function variants (PTCs, start loss and partial/full gene del) or missense variants affecting the homeodomain. > These consisted of three de novo variants, but for the majority of cases the variant was inherited from an unaffected parent, yielding an estimate for the penetrance of craniosynostosis of 12.5%. > These results were also supported by immunofluorescence analyses which showed that missense variants within the PRRX1 homeodomain cause abnormal nuclear localisation (PMID: 37154149) > Authors discuss how the previous reports of agnathia-otocephaly doesn't fit with this new evidence and they showed that a missense variant previously reported in a patient with agnathia-otocephaly p.(Phe113Leu) did not affect nuclear import. Supporting evidence: > Post-natal calvarial stem cells expressing Prrx1 have been shown to reside exclusively in the calvarial suture niche, suggesting a requirement for PRRX1 regarding suture patency during early development (PMID: 28366454) >Prrx1 has been shown to be widely expressed within the mouse coronal suture (PMID: 34376651) >Agnathia-otocephaly complex, 2 x missense variants (1 x het, 1 x hom) and 2 x frameshifts reported (het). The frameshift variants both occur in a poly A tract (PMID: 21294718, PMID: 22674740, PMID: 23444262, PMID: 22211708). Authors of the more recent publication on Craniosynostosis (PMID: 37154149) cast some doubt on the reports for Agnathia-otocephaly, possible explanations discussed are that this condition is AR and a 2nd hit was missed or another cause was not identified such as variants in OTX2. > PMID: 7758948 generated a loss-of-function mutation in the mouse Pmx1 gene. Mice homozygous for the mutant allele died soon after birth and exhibited defects of skeletogenesis, which involved the loss or malformation of craniofacial, limb, and vertebral skeletal structures. |
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| Mendeliome v1.1840 | PRRX1 |
Melanie Marty changed review comment from: > 17 individuals with Craniosynostosis from 14 families had been found to have rare heterozygous variants in PRRX1, loss of function variants (PTCs, start loss and partial/full gene del) or missense variants affecting the homeodomain. > These consisted of three de novo variants, but for the majority of cases the variant was inherited from an unaffected parent, yielding an estimate for the penetrance of craniosynostosis of 12.5%. > These results were also supported by immunofluorescence analyses which showed that missense variants within the PRRX1 homeodomain cause abnormal nuclear localisation (PMID: 37154149) > Authors discuss how the previous reports of agnathia-otocephaly doesn't fit with this new evidence and they showed that a missense variant previously reported in a patient with agnathia-otocephaly p.(Phe113Leu) did not affect nuclear import. Supporting evidence: > Post-natal calvarial stem cells expressing Prrx1 have been shown to reside exclusively in the calvarial suture niche, suggesting a requirement for PRRX1 regarding suture patency during early development (PMID: 28366454) >Prrx1 has been shown to be widely expressed within the mouse coronal suture (PMID: 34376651) >Agnathia-otocephaly complex, 2 x missense variants (1 x het, 1 x hom) and 2 x frameshifts reported (het). The frameshift variants both occur in a poly A tract (PMID: 21294718, PMID: 22674740, PMID: 23444262, PMID: 22211708).; to: > 17 individuals with Craniosynostosis from 14 families had been found to have rare heterozygous variants in PRRX1, loss of function variants (PTCs, start loss and partial/full gene del) or missense variants affecting the homeodomain. > These consisted of three de novo variants, but for the majority of cases the variant was inherited from an unaffected parent, yielding an estimate for the penetrance of craniosynostosis of 12.5%. > These results were also supported by immunofluorescence analyses which showed that missense variants within the PRRX1 homeodomain cause abnormal nuclear localisation (PMID: 37154149) > Authors discuss how the previous reports of agnathia-otocephaly doesn't fit with this new evidence and they showed that a missense variant previously reported in a patient with agnathia-otocephaly p.(Phe113Leu) did not affect nuclear import. Supporting evidence: > Post-natal calvarial stem cells expressing Prrx1 have been shown to reside exclusively in the calvarial suture niche, suggesting a requirement for PRRX1 regarding suture patency during early development (PMID: 28366454) >Prrx1 has been shown to be widely expressed within the mouse coronal suture (PMID: 34376651) >Agnathia-otocephaly complex, 2 x missense variants (1 x het, 1 x hom) and 2 x frameshifts reported (het). The frameshift variants both occur in a poly A tract (PMID: 21294718, PMID: 22674740, PMID: 23444262, PMID: 22211708). Authors of the more recent publication on Craniosynostosis (PMID: 37154149) cast some doubt on the reports for Agnathia-otocephaly, possible explanations discussed are that this condition is AR and a 2nd hit was missed or another cause was not identified such as variants in OTX2. |
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| Mendeliome v1.1840 | PRRX1 |
Melanie Marty changed review comment from: > 17 individuals with Craniosynostosis from 14 families had been found to have rare heterozygous variants in PRRX1, loss of function variants (PTCs, start loss and partial/full gene del) or missense variants affecting the homeodomain. > These consisted of three de novo variants, but for the majority of cases the variant was inherited from an unaffected parent, yielding an estimate for the penetrance of craniosynostosis of 12.5%. > These results were also supported by immunofluorescence analyses which showed that missense variants within the PRRX1 homeodomain cause abnormal nuclear localisation (PMID: 37154149) > Authors discuss how the previous reports of agnathia-otocephaly doen't fit with this new evidence and they showed that a missense variant previously reported in a patient with agnathia-otocephaly p.(Phe113Leu) did not affect nuclear import. Supporting evidence: > Post-natal calvarial stem cells expressing Prrx1 have been shown to reside exclusively in the calvarial suture niche, suggesting a requirement for PRRX1 regarding suture patency during early development (PMID: 28366454) >Prrx1 has been shown to be widely expressed within the mouse coronal suture (PMID: 34376651) >Agnathia-otocephaly complex, 2 x missense variants (1 x het, 1 x hom) and 2 x frameshifts reported (het). The frameshift variants both occur in a poly A tract (PMID: 21294718, PMID: 22674740, PMID: 23444262, PMID: 22211708).; to: > 17 individuals with Craniosynostosis from 14 families had been found to have rare heterozygous variants in PRRX1, loss of function variants (PTCs, start loss and partial/full gene del) or missense variants affecting the homeodomain. > These consisted of three de novo variants, but for the majority of cases the variant was inherited from an unaffected parent, yielding an estimate for the penetrance of craniosynostosis of 12.5%. > These results were also supported by immunofluorescence analyses which showed that missense variants within the PRRX1 homeodomain cause abnormal nuclear localisation (PMID: 37154149) > Authors discuss how the previous reports of agnathia-otocephaly doesn't fit with this new evidence and they showed that a missense variant previously reported in a patient with agnathia-otocephaly p.(Phe113Leu) did not affect nuclear import. Supporting evidence: > Post-natal calvarial stem cells expressing Prrx1 have been shown to reside exclusively in the calvarial suture niche, suggesting a requirement for PRRX1 regarding suture patency during early development (PMID: 28366454) >Prrx1 has been shown to be widely expressed within the mouse coronal suture (PMID: 34376651) >Agnathia-otocephaly complex, 2 x missense variants (1 x het, 1 x hom) and 2 x frameshifts reported (het). The frameshift variants both occur in a poly A tract (PMID: 21294718, PMID: 22674740, PMID: 23444262, PMID: 22211708). |
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| Mendeliome v1.1840 | PRRX1 |
Melanie Marty changed review comment from: > 17 individuals with Craniosynostosis from 14 families had been found to have rare heterozygous variants in PRRX1, loss of function variants (PTCs, start loss and partial/full gene del) or missense variants affecting the homeodomain. > These consisted of three de novo variants, but for the majority of cases the variant was inherited from an unaffected parent, yielding an estimate for the penetrance of craniosynostosis of 12.5%. > These results were also supported by immunofluorescence analyses which showed that missense variants within the PRRX1 homeodomain cause abnormal nuclear localisation (PMID: 37154149) > Authors discuss how the previous reports of agnathia-otocephaly don't fit with this new evidence and they showed that a missense variant previously reported in a patient with agnathia-otocephaly p.(Phe113Leu) did not affect nuclear import. Supporting evidence: > Post-natal calvarial stem cells expressing Prrx1 have been shown to reside exclusively in the calvarial suture niche, suggesting a requirement for PRRX1 regarding suture patency during early development (PMID: 28366454) >Prrx1 has been shown to be widely expressed within the mouse coronal suture (PMID: 34376651); to: > 17 individuals with Craniosynostosis from 14 families had been found to have rare heterozygous variants in PRRX1, loss of function variants (PTCs, start loss and partial/full gene del) or missense variants affecting the homeodomain. > These consisted of three de novo variants, but for the majority of cases the variant was inherited from an unaffected parent, yielding an estimate for the penetrance of craniosynostosis of 12.5%. > These results were also supported by immunofluorescence analyses which showed that missense variants within the PRRX1 homeodomain cause abnormal nuclear localisation (PMID: 37154149) > Authors discuss how the previous reports of agnathia-otocephaly doen't fit with this new evidence and they showed that a missense variant previously reported in a patient with agnathia-otocephaly p.(Phe113Leu) did not affect nuclear import. Supporting evidence: > Post-natal calvarial stem cells expressing Prrx1 have been shown to reside exclusively in the calvarial suture niche, suggesting a requirement for PRRX1 regarding suture patency during early development (PMID: 28366454) >Prrx1 has been shown to be widely expressed within the mouse coronal suture (PMID: 34376651) >Agnathia-otocephaly complex, 2 x missense variants (1 x het, 1 x hom) and 2 x frameshifts reported (het). The frameshift variants both occur in a poly A tract (PMID: 21294718, PMID: 22674740, PMID: 23444262, PMID: 22211708). |
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| Mendeliome v1.1840 | PRRX1 |
Melanie Marty changed review comment from: > 17 individuals with Craniosynostosis from 14 families had been found to have rare heterozygous variants in PRRX1, loss of function variants (PTCs, start loss and partial/full gene del) or missense variants affecting the homeodomain. > These consisted of three de novo variants, but for the majority of cases the variant was inherited from an unaffected parent, yielding an estimate for the penetrance of craniosynostosis of 12.5%. > These results were also supported by immunofluorescence analyses which showed that missense variants within the PRRX1 homeodomain cause abnormal nuclear localisation (PMID: 37154149) Supporting evidence: > Post-natal calvarial stem cells expressing Prrx1 have been shown to reside exclusively in the calvarial suture niche, suggesting a requirement for PRRX1 regarding suture patency during early development (PMID: 28366454) >Prrx1 has been shown to be widely expressed within the mouse coronal suture (PMID: 34376651); to: > 17 individuals with Craniosynostosis from 14 families had been found to have rare heterozygous variants in PRRX1, loss of function variants (PTCs, start loss and partial/full gene del) or missense variants affecting the homeodomain. > These consisted of three de novo variants, but for the majority of cases the variant was inherited from an unaffected parent, yielding an estimate for the penetrance of craniosynostosis of 12.5%. > These results were also supported by immunofluorescence analyses which showed that missense variants within the PRRX1 homeodomain cause abnormal nuclear localisation (PMID: 37154149) > Authors discuss how the previous reports of agnathia-otocephaly don't fit with this new evidence and they showed that a missense variant previously reported in a patient with agnathia-otocephaly p.(Phe113Leu) did not affect nuclear import. Supporting evidence: > Post-natal calvarial stem cells expressing Prrx1 have been shown to reside exclusively in the calvarial suture niche, suggesting a requirement for PRRX1 regarding suture patency during early development (PMID: 28366454) >Prrx1 has been shown to be widely expressed within the mouse coronal suture (PMID: 34376651) |
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| Mendeliome v1.332 | PTPA |
Zornitza Stark gene: PTPA was added gene: PTPA was added to Mendeliome. Sources: Literature Mode of inheritance for gene: PTPA was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: PTPA were set to 36073231 Phenotypes for gene: PTPA were set to Intellectual disability, MONDO: 36073231, PTPA-related Review for gene: PTPA was set to AMBER Added comment: Biallelic PTPA pathogenic variants lead to a form of ID with later-onset parkinsonism based on 4 individuals from 2 families in the literature. Affected individuals were homozygous for missense variants demonstrated to result to reduced mRNA and protein levels as well as PP2A complex activation. Drosophila studies support an age-dependent locomotor dysfunction. Variants in other PP2A-complex-related genes also lead to NDDs. Summary provided below. There is currently no associated phenotype in OMIM, G2P, PanelApp UK or SysID. Consider inclusion in relevant panels (ID, Parkinsonism/movement disorders, etc) with amber rating pending further reports. ------ Fevga, Tesson et al (2022 - PMID: 36073231) describe the features of 4 individuals, from 2 unrelated families, with biallelic pathogenic PTPA variants. These presented with normal or delayed early milestones, learning disability and ID (mild to moderate) followed by progressive signs of parkinsonism (at the age of 11 yrs in 2 sibs, 15 yrs in another individual). Motor symptoms were responsive to levodopa and later to deep brain stimulation. Linkage analysis in one consanguineous family followed by exome revealed homozygosity for a missense PTPA variant (NM_178001:c.893T>G/p.Met298Arg). Exome sequencing in affected subjects from the 2nd family revealed homozygosity for a further missense variant (c.512C>A/p.Ala171Asp). There were no other candidate variants for the phenotype following parental / segregation studies. Role of the gene: As the authors discuss, PTPA (or PPP2R4) is ubiquitously expressed in all tissues incl. brain and encodes a phosphotyrosyl phosphatase activator of the dimeric form of protein phosphatase-2A (PP2A). PP2A in turn, is the major Ser/Thr phosphatase in brain targeting a large number of proteins involved in diverse functions. Activation of PP2A is dependent on its methylation, which is negatively regulated by the PP2A-specific methylesterase (PME-1). By binding to PME-1, PTPA counteracts the negative influence of the former on PP2A. Pathogenic variants in genes encoding subunits/regulators of the PP2A complex (e.g. PPP2R1A or PPP2CA) are associated with neurodevelopmental disorders. Variant studies: Upon overexpression of wt and both variants in a HEK-293 cell line the authors demonstrated that both variants resulted in significantly reduced mRNA and protein levels (which for Ala171Asp were attributed to increased proteasomal degradation). Both variants were shown to result in impaired PP2A complex activation compared to wt. Drosophila / animal models: Pan-neuronal RNAi-mediated knockdown of ptpa in Drosophila resulted in an age-dependent locomotor dysfunction, reversible with L-DOPA treatment. Previous studies in mice suggest cognitive/electrophysiological impairments upon downregulation of PP2A activity in transgenic mice. Sources: Literature |
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| Mendeliome v1.323 | NODAL |
Zornitza Stark edited their review of gene: NODAL: Added comment: NODAL is a good biological candidate for heterotaxy disorders, and this is supported by animal models. The gene is depleted for LoF variants in gnomad. The missense variants reported in PMIDs 9354794 and 19064609 are present at a high population frequency in gnomad, including some in homozygous case: their association with disease is DISPUTED. A total of at least 7 families reported with severe CHD and high impact variants (stop gain, frameshift and canonical splice site). However, almost invariably these were inherited from unaffected or questionably affected parents (e.g. self reports of heart murmur in childhood), raising questions about whether these variants contribute to disease under a monogenic or polygenic model and/or about penetrance. Discussed at GenCC on 13/9/2022 and agreed on MODERATE assessment.; Changed rating: AMBER; Changed publications: 9354794, 19064609, 29368431, 19933292, 11311163, 30293987 |
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| Mendeliome v1.247 | ZMYND8 |
Zornitza Stark gene: ZMYND8 was added gene: ZMYND8 was added to Mendeliome. Sources: Expert Review Mode of inheritance for gene: ZMYND8 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: ZMYND8 were set to 35916866; 32530565 Phenotypes for gene: ZMYND8 were set to Neurodevelopmental disorder, MONDO:0700092, ZMYND8-related; Delayed speech and language development; Motor delay; Intellectual disability; Abnormality of cardiovascular system morphology; Hearing abnormality; Abnormality of vision; Abnormality of the face; Seizures Review for gene: ZMYND8 was set to GREEN Added comment: Dias et al (2022 - PMID: 35916866) describe the phenotype of 11 unrelated individuals with monoallelic de novo (or suspected de novo) missense (N=9) or truncating (N=2) ZMYND8 variants. One of these subjects was previously reported by Suzuki et al (2020 - PMID: 32530565). Features included speech delay/language difficulties (9/11), motor delay (9/11), ID (in 10/11 - profound in 1, moderate in 2), CHD (7/11 - PDA, VSD, ASD, pulmonary stenosis, etc), hearing or vision impairment (7/11). Seizures were reported in few (in text 5/11, table 2/11). Variable non-familial facial features were present in (9/11). As the authors discuss, ZMYND8 encodes a multidomain protein playing a role in transcription regulation, chromatin remodeling, regulation of super enhancers, DNA damage response/tumor suppression. The protein is broadly expressed in brain and shows highest expression in early development. Molecular modeling and/or a yeast two-hybrid system were suggestive of disrupted interaction of ZMYND8 with Drebrin (missense variants in PWWP domain) or GATAD2A (variants in MYND domain). Neuronal Zmynd8 knockdown in Drosophila resulted in deficits in habituation learning. Sources: Expert Review |
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| Mendeliome v0.11471 | ISCU | Zornitza Stark Marked gene: ISCU as ready | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mendeliome v0.11471 | ISCU | Zornitza Stark Gene: iscu has been classified as Green List (High Evidence). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mendeliome v0.11471 | ISCU | Zornitza Stark Phenotypes for gene: ISCU were changed from to Myopathy with lactic acidosis, hereditary, MIM# 255125 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mendeliome v0.11470 | ISCU | Zornitza Stark Publications for gene: ISCU were set to | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mendeliome v0.11469 | ISCU | Zornitza Stark Mode of inheritance for gene: ISCU was changed from Unknown to BOTH monoallelic and biallelic, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mendeliome v0.11468 | ISCU |
Zornitza Stark Tag deep intronic tag was added to gene: ISCU. Tag founder tag was added to gene: ISCU. |
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| Mendeliome v0.11468 | ISCU | Zornitza Stark reviewed gene: ISCU: Rating: GREEN; Mode of pathogenicity: None; Publications: 29079705, 18304497, 18296749, 19567699; Phenotypes: Myopathy with lactic acidosis, hereditary, MIM# 255125; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mendeliome v0.11071 | CHKA |
Konstantinos Varvagiannis gene: CHKA was added gene: CHKA was added to Mendeliome. Sources: Literature Mode of inheritance for gene: CHKA was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: CHKA were set to 35202461 Phenotypes for gene: CHKA were set to Abnormal muscle tone; Global developmental delay; Intellectual disability; Seizures; Microcephaly; Abnormality of movement; Abnormality of nervous system morphology; Short stature Penetrance for gene: CHKA were set to Complete Review for gene: CHKA was set to GREEN Added comment: Klöckner (2022 - PMID: 35202461) describe the phenotype of 6 individuals (from 5 unrelated families) harboring biallelic CHKA variants. Shared features incl. abnormal muscle tone(6/6 - hypertonia or hypotonia, 3/6 each), DD/ID (6/6,severe in 4, severe/profound in 2), epilepsy (6/6 - onset: infancy - 3y2m | epileptic spasms or GS at onset), microcephaly (6/6), movement disorders (3/6 - incl. dyskinesia, rigidity, choreoatetotic movements). 2/5 individuals exhibited MRI abnormalities, notably hypomyelination. Short stature was observed in 4/6. Eventual previous genetic testing was not discussed. Exome sequencing (quattro ES for 2 sibs, trio ES for 1 individual, singleton for 3 probands) revealed biallelic CHKA variants in all affected individuals. Sanger sequencing was performed for confirmation and segregation studies. Other variants (in suppl.) were not deemed to be causative for the neurodevelopmental phenotype. 3 different missense, 1 start-loss and 1 truncating variant were identified, namely (NM_0012772.2): - c.421C>T/p.(Arg141Trp) [3 hmz subjects from 2 consanguineous families], - c.580C>T/p.Pro194Ser [1 hmz individual born to consanguineous parents], - c.2T>C/p.(Met1?) [1 hmz individual born to related parents], - c.14dup/p.(Cys6Leufs*19) in trans with c.1021T>C/p.(Phe341Leu) in 1 individual. CHKA encodes choline kinase alpha, an enzyme catalyzing the first step of phospholipid synthesis in the Kennedy pathway. The pathway is involved in de novo synthesis of glycerophospholipids, phosphatidylcholine and phosphatidylethanolamine being the most abundant in eukaryotic membranes. CHKA with its paralog (CHKB) phosphorylates either choline or ethanolamine to phosphocholine or phosphoethanolamine respectively with conversion of ATP to ADP. As the authors comment, biallelic pathogenic variants in CHKB cause a NDD with muscular dystrophy, hypotonia, ID, microcephaly and structural mitochondrial anomalies (MIM 602541). [Prominent mitochondrial patterning was observed in a single muscle biopsy available from an individual with biallelic CHKA variants]. Other disorders of the Kennedy pathway (due to biallelic PCYT2, SELENOI, PCYT1A variants) present with overlapping features incl. variable DD/ID (no-severe), microcephaly, seizures, visual impairment etc. CHKA variants were either absent or observed once in gnomAD, affected highly conserved AAs with multiple in silico predictions in favor of a deleterious effect. In silico modeling suggests structural effects for several of the missense variants (Arg141Trp, Pro194Ser presumably affect ADP binding, Phe341 lying close to the binding site of phosphocholine). Each of the missense variants was expressed in yeast cells and W. Blot suggested expression at the expected molecular weight at comparative levels. The 3 aforementioned variants exhibited reduced catalytic activity (20%, 15%, 50% respectively). NMD is thought to underly the deleterious effect of the frameshift one (not studied). The start-loss variant is expected to result in significantly impaired expression and protein function as eventual utilization of the next possible start codon - occurring at position 123 - would remove 26% of the protein. Chka(-/-) is embryonically lethal in mice, suggesting that complete loss is not compatible with life. Reduction of choline kinase activity by 30% in heterozygous mice did not appear to result in behavioral abnormalities although this was not studied in detail (PMID cited: 18029352). Finally, screening of 1566 mouse lines identified 198 genes whose disruption yields neuroanatomical phenotypes, Chka(+/-) mice being among these (PMID cited: 31371714). There is no associated phenotype in OMIM, Gene2Phenotype or SysID. Overall this gene can be considered for inclusion in the ID and epilepsy panes with green or amber rating (>3 individuals, >3 variants, variant studies, overlapping phenotype of disorders belonging to the same pathway, etc). Consider also inclusion in the microcephaly panel (where available this seemed to be of postnatal onset). Sources: Literature |
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| Mendeliome v0.8824 | PLXNA2 |
Zornitza Stark gene: PLXNA2 was added gene: PLXNA2 was added to Mendeliome. Sources: Literature Mode of inheritance for gene: PLXNA2 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: PLXNA2 were set to 34327814 Phenotypes for gene: PLXNA2 were set to Intellectual disability; Abnormality of the face; Failure to thrive; Abnormal heart morphology Review for gene: PLXNA2 was set to AMBER Added comment: Altuame et al (2021 - PMID: 34327814) describe 3 individuals from 2 consanguineous Arab families with biallelic PLXNA2 variants. The index patient from the 1st family presented with CHD (hypoplastic right ventricle, ASD), DD and moderate ID (IQ of 40), failure to thrive as well as some dysmorphic features (obtuse mandibular angle, mild overbite, synophrys with downslanting p-f, strabismus, etc). There were additional features (eg. postaxial polydactyly) which were found in other affected and unaffected family members. Exome sequencing with autozygome analysis revealed homozygosity for a PLXNA2 stopgain variant (NM_025179:c.3603C>A / p.(Cys1201*)). Sanger confirmation was carried out and segregation analyses confirmed carrier status of the unaffected parents and a sib as well as a brother homozygous for the same variant. Clinical evaluation of the latter, following this finding revealed borderline intellectual functioning, ADHD, failure to thrive. There was no mandibular anomaly or overbite and no clinical evidence of CHD (no echo performed). The index patient from the 2nd consanguineous family was evaluated for ID (IQ of 63), with previous borderline motor development, ADHD and some dysmorphic features (obtuse mandibular angle and overbite). There was no clinical evidence of CHD (no echo performed). Exome sequencing with autozygosity mapping revealed a homozygous missense PLXNA2 variant (c.3073G>A / p.(Asp1025Asn), present only once in gnomAD (htz), with rather non-concordant in silico predictions SIFT 0.22, PolyPhen 0.682 and CADD 23.5. The aa was however highly conserved. Segregation analysis confirmed carrier state of the parents and 2 unaffected sibs, with a 3rd sib homozygous for the wt allele. As the authors discuss: *PLXNA2 belongs to the plexin family of genes, encoding transmbembrane proteins functioning as semaphorin receptors. It has predominant expression in neural tissue. The protein is thought to bind semaphorin-3A, -3C or -5 followed by plexin A2 dimerization, activation of its GTPase-activating protein domain, negative regulation of Rap1B GTPase and initiation of a signal transduction cascade mediating axonal repulsion/guidance, dendritic guidance, neuronal migration. *Murine Plxna2 knockout models display structural brain defects. In addition they display congenital heart defects incl. persistent truncus arteriosus and interrupted aortic arch. *Rare CNVs in adult humans with tetralogy of Fallot have suggested a potential role of PLXNA2 in cardiac development and CHD. *Expression and the role of PLXNA2 in human chondrocytes as well as a GWAS in 240 japanese patients with mandibular prognathism where PLXNA2 was suggested as a susceptibility locus. Overall, the authors recognize some common features (as for cognitive functioning, some dysmorphic features incl. obtuse mandibular angle and overbite in 2 unrelated subjects, failure to thrive 3/3) and provide plausible explanations for the variability / discordance of others eg: - Cyanotic heart disease explaining discordance in cognitive outcome among sibs - Incomplete penetrance for CHD (and/or ID or mandibular anomaly) as for few AR disorders and/or - Additional pathogenic variants possibly explaining the CHD in the first subject. There is no associated phenotype in OMIM or G2P. SysID includes PLXNA2 among the candidate ID genes. Sources: Literature |
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| Mendeliome v0.8807 | VPS50 |
Zornitza Stark gene: VPS50 was added gene: VPS50 was added to Mendeliome. Sources: Literature Mode of inheritance for gene: VPS50 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: VPS50 were set to 34037727 Phenotypes for gene: VPS50 were set to Neonatal cholestatic liver disease; Failure to thrive; Profound global developmental delay; Postnatal microcephaly; Seizures; Abnormality of the corpus callosum Review for gene: VPS50 was set to AMBER Added comment: Schneeberger et al (2021 - PMID: 34037727) describe the phenotype of 2 unrelated individuals with biallelic VPS50 variants. Common features included transient neonatal cholestasis, failure to thrive, severe DD with failure to achieve milestones (last examination at 2y and 2y2m respectively), postnatal microcephaly, seizures (onset at 6m and 25m) and irritability. There was corpus callosum hypoplasia on brain imaging. Both individuals were homozygous for variants private to each family (no/not known consanguinity applying to each case). The first individual was homozygous for a splicing variant (NM_017667.4:c.1978-1G>T) and had a similarly unaffected sister deceased with no available DNA for testing. The other individual was homozygous for an in-frame deletion (c.1823_1825delCAA / p.(Thr608del)). VPS50 encodes a critical component of the endosome-associated recycling protein (EARP) complex, which functions in recycling endocytic vesicles back to the plasma membrane [OMIM based on Schindler et al]. The complex contains VPS50, VPS51, VPS52, VPS53, the three latter also being components of GARP (Golgi-associated-retrograde protein) complex. GARP contains VPS54 instead of VPS50 and is required for trafficking of proteins to the trans-golgi network. Thus VPS50 (also named syndetin) and VPS54 function in the EARP and GARP complexes, to define directional movement of their endocytic vesicles [OMIM based on Schindler et al]. The VPS50 subunit is required for recycling of the transferrin receptor. As discussed by Schneeberger et al (refs provided in text): - VPS50 has a high expression in mouse and human brain as well as throughout mouse brain development. - Mice deficient for Vps50 have not been reported. vps50 knockdown in zebrafish results in severe developmental defects of the body axis. Knockout mice for other proteins of the EARP/GARP complex (e.g. Vps52, 53 and 54) display embryonic lethality. Studies performed by Schneeberger et al included: - Transcript analysis for the 1st variant demonstrated skipping of ex21 (in patient derived fabriblasts) leading to an in frame deletion of 81 bp (r.1978_2058del) with predicted loss of 27 residues (p.Leu660_Leu686del). - Similar VPS50 mRNA levels but significant reduction of protein levels (~5% and ~8% of controls) were observed in fibroblasts from patients 1 and 2. Additionally, significant reductions in the amounts of VPS52 and VPS53 protein levels were observed despite mRNA levels similar to controls. Overall, this suggested drastic reduction of functional EARP complex levels. - Lysosomes appeared to have similar morphology, cellular distribution and likely unaffected function in patient fibroblasts. - Transferrin receptor recycling was shown to be delayed in patient fibroblasts suggestive of compromise of endocytic-recycling function. As the authors comment, the phenotype of both individuals with biallelic VPS50 variants overlaps with the corresponding phenotype reported in 15 subjects with biallelic VPS53 or VPS51 mutations notably, severe DD/ID, microcephaly and early onset epilepsy, CC anomalies. Overall, for this group, they propose the term "GARP and/or EARP deficiency disorders". There is no VPS50-associated phenotype in OMIM or G2P. SysID includes VPS50 among the ID candidate genes. Sources: Literature |
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| Mendeliome v0.8741 | TCF7L2 |
Zornitza Stark changed review comment from: 2 reviews Konstantinos Varvagiannis (Other) I don't know Dias et al (2021 - PMID: 34003604) describe the phenotype of 11 unrelated individuals harboring de novo missense/truncating TCF7L2 variants. Features included DD in childhood (motor delay in 8/11, speech delay in 11/11), intellectual abilities ranging from average cognitive functioning to mild/moderate ID (the latter observed in 5/11), myopia (6/11) , dysmorphic features, variable orthopedic findings, and neuropsychiatric comorbidities incl. ASD (4/11) / ADHD (4/11). One additional (12th) individual was excluded from this summary due to concurrent diagnosis of hypoxic-ischemic injury. TCF7L2 on 10q25 encodes transcription factor 7-like 2, a high mobility group (HMG) box-containing transcription factor. As the authors discuss, the protein mediates canonical Wnt signaling. Secreted Wnt proteins lead to release of beta-catenin (CTNNB1) which after translocation to the nucleus acts with DNA-binding factors incl. TCF7L2 to turn on Wnt-responsive target genes. As a result TCF7L2 acts with beta-catenin as a switch for transcriptional regulation. Multiple alternative spliced TCF7L2 transcripts mediate it's function and specificity of transcriptional repertoire in a variety of tissues and contexts. Dias et al provide references for its role in nervous system development incl. neurogenesis and thalamic development. Variants in all cases occurred as de novo events with pLoF (stopgain, frameshift, splicing) ones predicted to lead to NMD. Missense variants occurred in all cases in or adjacent to the HMG box domain [aa 350-417]. 5 different missense variants affecting 3 residues were reported incl. c.1142A>C, c.1143C>G (leading to Asn381Thr/Lys respectively), c.1250G>T (Trp417Leu), c.1267T>C, c.1268A>G (leading to Tyr423His/Cys) [NM_001146274.1]. The gene has a pLI of 0.99-1 gnomAD/ExAC while there is a region of missense constraint encompassing the HMG box domain (the latter is an evolutionary conserved region mediating interactions with DNA). No phenotypic differences were observed among individuals with pLoF and missense SNVs, and haploinsufficiency is presumed to be the underlying mechanism. There are no variant or other studies performed, nor any animal models discussed. In supplementary table 2, the authors provide several references to previous large scale sequencing studies with brief/incomplete descriptions of individuals de novo TCF7L2 variants and neurodevelopmental disorder (ID/ASD - Iossifov, De Rubeis, Lelieveld, McRae/DDD study and many other Refs). Heterozygous TCF7L2 variants are thought to confer susceptibility to type diabetes mellitus (MIM 125853). Individuals reported by Dias et al did not have endocrine abnormalities including DM. A study by Roychowdhury et al (2021 - PMID: 34265237) suggests that regulatory variants in TCF7L2 are associated with thoracic aneurysm. There is no other associated phenotype (notably NDD) in OMIM. G2P includes TCF7L2 in its DD panel (Disease : TC7L2-related DD, Confidence:confirmed, Monoallelic, LoF). SysID includes this gene within the autism candidate genes and current primary ID genes.; to: Dias et al (2021 - PMID: 34003604) describe the phenotype of 11 unrelated individuals harboring de novo missense/truncating TCF7L2 variants. Features included DD in childhood (motor delay in 8/11, speech delay in 11/11), intellectual abilities ranging from average cognitive functioning to mild/moderate ID (the latter observed in 5/11), myopia (6/11) , dysmorphic features, variable orthopedic findings, and neuropsychiatric comorbidities incl. ASD (4/11) / ADHD (4/11). One additional (12th) individual was excluded from this summary due to concurrent diagnosis of hypoxic-ischemic injury. TCF7L2 on 10q25 encodes transcription factor 7-like 2, a high mobility group (HMG) box-containing transcription factor. As the authors discuss, the protein mediates canonical Wnt signaling. Secreted Wnt proteins lead to release of beta-catenin (CTNNB1) which after translocation to the nucleus acts with DNA-binding factors incl. TCF7L2 to turn on Wnt-responsive target genes. As a result TCF7L2 acts with beta-catenin as a switch for transcriptional regulation. Multiple alternative spliced TCF7L2 transcripts mediate it's function and specificity of transcriptional repertoire in a variety of tissues and contexts. Dias et al provide references for its role in nervous system development incl. neurogenesis and thalamic development. Variants in all cases occurred as de novo events with pLoF (stopgain, frameshift, splicing) ones predicted to lead to NMD. Missense variants occurred in all cases in or adjacent to the HMG box domain [aa 350-417]. 5 different missense variants affecting 3 residues were reported incl. c.1142A>C, c.1143C>G (leading to Asn381Thr/Lys respectively), c.1250G>T (Trp417Leu), c.1267T>C, c.1268A>G (leading to Tyr423His/Cys) [NM_001146274.1]. The gene has a pLI of 0.99-1 gnomAD/ExAC while there is a region of missense constraint encompassing the HMG box domain (the latter is an evolutionary conserved region mediating interactions with DNA). No phenotypic differences were observed among individuals with pLoF and missense SNVs, and haploinsufficiency is presumed to be the underlying mechanism. There are no variant or other studies performed, nor any animal models discussed. In supplementary table 2, the authors provide several references to previous large scale sequencing studies with brief/incomplete descriptions of individuals de novo TCF7L2 variants and neurodevelopmental disorder (ID/ASD - Iossifov, De Rubeis, Lelieveld, McRae/DDD study and many other Refs). Heterozygous TCF7L2 variants are thought to confer susceptibility to type diabetes mellitus (MIM 125853). Individuals reported by Dias et al did not have endocrine abnormalities including DM. A study by Roychowdhury et al (2021 - PMID: 34265237) suggests that regulatory variants in TCF7L2 are associated with thoracic aneurysm. There is no other associated phenotype (notably NDD) in OMIM. G2P includes TCF7L2 in its DD panel (Disease : TC7L2-related DD, Confidence:confirmed, Monoallelic, LoF). SysID includes this gene within the autism candidate genes and current primary ID genes. |
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| Mendeliome v0.8522 | SYNCRIP |
Zornitza Stark gene: SYNCRIP was added gene: SYNCRIP was added to Mendeliome. Sources: Literature Mode of inheritance for gene: SYNCRIP was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: SYNCRIP were set to 34157790; 30504930; 27479843; 23020937 Phenotypes for gene: SYNCRIP were set to Global developmental delay; Intellectual disability; Autism; Myoclonic atonic seizures; Abnormality of nervous system morphology Review for gene: SYNCRIP was set to GREEN Added comment: Semino et al (2021 - PMID: 34157790) provide clinical details on 3 unrelated individuals with de novo SYNCRIP variants and provide a review of 5 additional subjects previously identified within large cohorts in the literature and databases. Features included DD, ID (7/7 for whom this information was available), ASD or autistic features (4/7). MRI abnormalities were observed in 3 (widening of CSF spaces, periventricular nodular heterotopia, prominent lat. ventricles). Epilepsy (myoclonic-astatic epilepsy / Doose syndrome) was reported for 2(/8) individuals. The 3 patients here reported were identified following trio/singleton exome with Sanger confirmation of the variants and their de novo occurrence. Variants are in almost all cases de novo (7/7 for whom this was known) and in 5/8 cases were pLoF, in 2/8 missense SNVs while a case from DECIPHER had a 77.92 kb whole gene deletion not involving other genes with unknown inheritance. Overall the variants reported to date include [NM_006372.5]: 1 - c.858_859del p.(Gly287Leufs*5) 2 - c.854dupA p.(Asn285Lysfs*8) 3 - c.734T>C p.(Leu245Pro) 4 - chr6:85605276-85683190 deletion (GRCh38) 5 - c.629T>C p.(Phe210Ser) 6 - c.1573_1574delinsTT p.(Gln525Leu) 7 - c.1247_1250del p.(Arg416Lysfs*145) 8 - c.1518_1519insC p.(Ala507Argfs*14) [P1-3: this report, P4: DECIPHER 254774, P5-6: Guo et al 2019 - PMID: 30504930, P7: Lelieveld et al 2016 - PMID: 27479843, P8: Rauch et al 2012 - PMID: 23020937 / all other Refs not here reviewed, clinical details summarized by Semino et al in table 1] SYNCRIP (also known as HNRNPQ) encodes synaptotagmin‐binding cytoplasmic RNA‐interacting protein. As the authors note, this RNA-binding protein is involved in multiple pathways associated with neuronal/muscular developmental disorders. Several references are provided for its involvement in regulation of RNA metabolism, among others sequence recognition, pre-mRNA splicing, translation, transport and degradation. Mutations in other RNA-interacting proteins and hnRNP members (e.g. HNRNPU, HNRNPD) are associated with NDD. The missense variant (p.Leu245Pro) is within RRM2 one of the 3 RNA recognition motif (RRM) domains of the protein. These 3 domains, corresponding to the central part of the protein (aa 150-400), are relatively intolerant to variation (based on in silico predictions and/or variation in gnomAD). Leu245 localizes within an RNA binding pocket and in silico modeling suggests alteration of the tertiary structure and RNA-binding capacity of RRM2. There are no additional studies performed. Overall haploinsufficiency appears to be the underlying disease mechanism based on the truncating variants and the gene deletion. [pLI in gnomAD : 1, %HI : 2.48%] Animal models are not discussed. There is no associated phenotype in OMIM. This gene is included in the DD panel of G2P (monoallelic LoF variants / SYNCRIP-related developmental disorder). SysID also lists SYNCRIP within the current primary ID genes. Sources: Literature |
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| Mendeliome v0.8263 | EPHA7 |
Zornitza Stark gene: EPHA7 was added gene: EPHA7 was added to Mendeliome. Sources: Expert Review Mode of inheritance for gene: EPHA7 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: EPHA7 were set to 34176129 Phenotypes for gene: EPHA7 were set to Intellectual disability Review for gene: EPHA7 was set to AMBER Added comment: Lévy et al (2021 - PMID: 34176129) provide evidence that haploinssuficiency of EPHA7 results in a neurodevelopmental disorder. The authors report on 12 individuals belonging to 9 unrelated families, all harboring with 6q microdeletions spanning EPHA7. Overlapping features included DD (13/13), ID (10/10 - mild in most cases, individuals with larger CNVs/additional variants had more severe phenotype), speech delay and behavioral disorders. Variable other features incl. hypotonia (70%), non specific facial features, eye abnormalities (40%) and cardiac defects (25%). The CNVs ranged from 152 kb to few Mb in size but in 4 subjects (P5-8) were only minimal, involving only EPHA7. 9 out of 12 individuals had inherited the deletion (5 subjects paternal, 4 maternal), in 1 subject (P12) this occured de novo, while for 2 others inheritance was not specified. Most deletions were inherited from an unaffected parent (in 6/7 families), with unclear contribution in a further one. The authors discuss on previous studies suggesting an important role for EphA7 in brain development (modulation of cell-cell adhesion and repulsion, regulation of dendrite morphogenesis in early corticogenesis, role in dendritic spine formation later in development. EphA7 has also been proposed to drive neuronal maturation and synaptic function). Haploinsufficiency for other ephrins or ephrin receptors has been implicated in other NDDs. Overall Lévy et al promote incomplete penetrance and variable expressivity with haploinsufficiency of this gene being a risk factor for NDD. [The gene has also an %HI of 2.76% and a pLI of 1]. Sources: Expert Review |
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| Mendeliome v0.4874 | ITFG2 |
Zornitza Stark gene: ITFG2 was added gene: ITFG2 was added to Mendeliome. Sources: Literature Mode of inheritance for gene: ITFG2 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: ITFG2 were set to 28397838; https://doi.org/10.1038/s41525-020-00150-z Phenotypes for gene: ITFG2 were set to Neurodevelopmental abnormality; Intellectual disability; Developmental regression; Ataxia Review for gene: ITFG2 was set to AMBER Added comment: ITFG2 was suggested to be a candidate gene for autosomal recessive ID in the study by Harripaul et al (2018 - PMID: 28397838). The authors performed microarray and exome sequencing in 192 consanguineous families and identified a homozygous ITGF2 stopgain variant (NM_018463.3:c.472G>T / p.Glu158*) along with 3 additional variants segregating with ID within an investigated family (PK51). Cheema et al (2020 - https://doi.org/10.1038/s41525-020-00150-z) report briefly on a male, born to consanguineous parents presenting with NDD, seizures, regression and ataxia. There was a similarly affected female sibling. Evaluation of ROH revealed a homozygous ITFG2 nonsense variant [NM_018463.3:c.361C>T / p.(Gln121*)]. Families in this study were investigated by trio WES or WGS. Evaluation of data of the same lab revealed 3 additional unrelated subjects with overlapping phenotypes, notably NDD and ataxia. These individuals were - each - homozygous for pLoF variants [NM_018463.3:c.848-1G>A; NM_018463.3:c.704dupC, p.(Ala236fs), NM_018463.3:c.1000_1001delAT, p.(Ile334fs)]. As discussed in OMIM, ITFG2 encodes a subunit of the KICSTOR protein complex, having a role in regulating nutrient sensing by MTOR complex-1 (Wolfson et al 2017 - PMID : 28199306). Rated Amber as Cheema et al report on diagnostic outcomes and multiple candidate genes as part of a heterogenous cohort and details are therefore limited. Sources: Literature |
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| Mendeliome v0.4520 | SLC12A2 |
Zornitza Stark edited their review of gene: SLC12A2: Added comment: Monoallelic : DD/ID was a feature in >= 6 individuals with monoallelic de novo SLC12A2. An individual with an exon 22 truncating variant was reported to have normal milestones and cognitive function. Exon 21 variants have been described in individuals with rather isolated hearing impairment (possibly some associated motor delay, but normal cognition). Hearing impairment was also reported in 2/6 patients with variants in other exons (1 missense / 1 frameshift). Biallelic : DD/ID was reported in at least 3 individuals in literature. Hearing impairment has been reported on 2 occasions (although this was not probably evaluated in all subjects). --- Monoallelic SLC12A2 mutations : ► Individuals with de novo mutations and developmental disorder were first identified by the DDD study (2017 - PMID: 28135719). 5 of them have been reported in detail by McNeill et al (below). ► McNeill et al (2020 - PMID: 32658972) report on 6 individuals with neurodevelopmental disorder due to de novo SLC12A2 mutation. All presented DD or ID ranging from mild to severe. ASD was reported in 3/6. Sensorineural hearing loss was a feature in 2/6 with the remaining having normal formal evaluations. Brain, cardiac and/or additional malformations were reported in a single individual. Following non-diagnostic prior work-up (CMA, FMR1 or other investigations) trio exome sequencing revealed missense (4/6) or truncating variants (2/6). Three additional individuals (incl. a father and his son) with missense variants in exon 21 (NM_001046.3 / p.Glu979Lys and p.Glu980Lys) presented with bilateral sensorineural hearing loss. Speech and/or motor delay reported in these cases were attributed to the hearing impairment/vestibular arreflexia (cognitive abilities not tested). SLC12A2 encodes sodium-potassium-chloride transporter 1 (also NKCC1). The GTEx project has identified 8 isoforms. In brain both exon 21-containing/deleted isoforms are expressed (cited Morita et al 2014 - PMID: 24695712). As the authors discuss, RNA-seq of the developing mouse cochlea suggests that the exon 21 containing isoform is the single transcript expressed. Evidence from RNA-seq data (BrainSpan project) and literature suggests that the significant amounts of exon 21 lacking isoforms in fetal brain compensate for the deleterious effects of exon 21 variants and explain the lack of NDD in relevant patients. Slc12a2 (NKCC1) null mouse model has demonstrated that the transporter plays a role in accumulation of the potassium rich endolymph in the inner ear, with NKCC1 absence causing sensorineural deafness and imbalance. Slc12a2 display cochlear malformations, loss of hair cells and hearing impairment (cited Delpire et al 1999 - PMID: 10369265). The brain phenotype has not been studied extensively, although loss of Slc12a2 has been shown to inhibit neurogenesis (cited: Magalhães and Rivera et al. - PMID: 27582690). Slc12a2 null zebrafish display a collapse of the otic vesicle and reduced endolymph (Abbas and Whitfield, 2009 - PMID: 19633174) relevant to the human hearing disorder. In vitro assessment of NKCC1 ion transporter function in Xenopus laevis, supported the deleterious effect of the identified variants (significant reduction in K+ influx). Using available single cell RNA-seq data the authors further demonstrated that SLC12A2 expressing cells display transcriptomic profiles reflective of active neurogenesis. ► Delpire et al (2016 - PMID: 27900370 - not reviewed in detail) described a 13 y.o. girl harboring a de novo 11-bp deletion in SLC12A2 exon 22. This individual reached developmental milestones on time and had a NORMAL cognitive function. Hearing was seemingly normal. Features included orthostatic intolerance, respiratory weakness, multiple endocrine abnormalities, pancreatic insufficiency and multiorgan failure incl. gut and bladder. Exome in the proband, parents and 3 unaffected sibs suggested SLC12A2 as the only candidate for her phenotype. Functional analyses in Xenopus laevis oocytes suggested that a non functional transporter was expressed and trafficked to the membrane as the wt. Detection of the truncated protein at higher molecular sizes suggested either enhanced dimerization or misfolded aggregate. There was no dominant-negative effect of mutant NKCC1. In patient fibroblasts a reduced total and NKCC1-mediated K+ influx. ► Mutai et al (2020 - PMID: 32294086) report on several individuals from 4 families, harboring variants within exon 21 or - in one case - at it's 3' splice-site (leading to skipping oe this exon at the mRNA level). All subjects were investigated for severe/profound hearing loss (in line with the role of exon 21-included isoforms in cochlea. The variant segregated with hearing impairment in 3 generations of a family while in all other subjects the variant had occured as de novo event. Despite motor delays (e.g. the subject from fam2 could not hold head or sit at the age of 10m / the proband in Fam3 was able to hold his head and walk at 6 and 20 m respectively) behavior and cognition were commented to be within normal range. ----- Biallelic SLC12A2 mutations: ► Anazi et al (2017 - PMID: 29288388) briefly reported on a 3 y.o. boy (17DG0776) with central hypotonia, neonatal respiratory distress, failure to thrive, global DD and microcephaly and a skeletal survey suggestive of osteopenia. After non-diagnostic prior investigations (CMA revealing a 1p duplication classified as VUS, extensive metabolic workup), WES revealed a homozygous SLC12A2 splicing variant [NM_001046.2:c.2617-2A>G]. ► Macnamara et al (2019 - PMID: 30740830) described a 5.5 y.o. male with sensorineural hearing loss, profound delays in all developmental areas among several other features (choanal atresia, failure to thrive, respiratory problems, absent sweat and tear production or salivation, GI abnormalities). Genetic testing for several disorders considered (cystic fibrosis, spinal muscular atrophy, sequencing and del/dup analysis of mtDNA) was normal. CMA revealed paternal uniparental isodisomy for chr. 5 and WGS a homozygous 22kb deletion in SLC12A2. This was followed by confirmation of homozygosity in the proband, heterozygosity of the unaffected father, delineation of breakpoints (chr5:127441491-127471419). mRNA studies in patient fibroblasts confirmed deletion of ex2-7, splicing of ex1 directly to ex8 and introduction of a premature stop codon in ex9. qRT-PCR confirmed that mRNA is likely subjected to NMD (expression ~80% of control). Western blot confirmed absence of the protein in the patient's fibroblasts. Again mouse models are thought to recapitulate the hearing defect but also the deficient saliva production (cited Evans et al 2000 - PMID: 10831596). Again the authors speculate a role of SLC12A2 in brain development based on evidence from murine models (migration, dendritic growth, increse in neuron density through regulation of GABAergic signalling (Young et al 2012 - PMID: 23015452). Hypotheses are also made on a regulatory relationship between NKCC1 and CFTR based on mRNA data from the ko mouse model. ► Stödberg et al (2020 - PMID: 32754646) reported 2 sibs with a complex neurodevelopmental disorder due to compound heterozygosity for a frameshift SLC12A2 variant and a splicing one (NM_001046:c.1431delT and c.2006-1G>A). Both presented hypotonia, neonatal S. aureus parotitis and respiratory problems (incl. apneas). While the older sib died at the age of 22 days, the younger one had persistent respiratory issues incl. a dry respiratory mucosa motivating metabolic, immunology investigations and testing for CF. She displayed microcephaly (OFC -2.5 SD, H was also -3.5SD), severe intellectual disability. MRI was suggestive of white matter and basal ganglia abnormalities. Other features incl. hearing impairment, and lack of tears,saliva and sweat, constipation and intestinal malrotation. There was facial dysmorphism. The variants were the only retained following WGS of the 2 affected sisters, parents and an unaffected brother. The splicing variant was shown to result in skipping of exon 13, while the indel in NMD. Again the authors discuss that the deficient saliva production, impaired hearing and GI problems are recapitulated in the mouse model (several refs provided).; Changed rating: GREEN; Changed publications: 28135719, 32658972, 27900370, 32294086, 29288388, 30740830, 32754646; Changed phenotypes: Kilquist syndrome, deafness, intellectual disability, dysmorphic features, absent salivation, ectodermal dysplasia, constipation, intestinal malrotation, multiple congenital anomalies; Changed mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal |
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| Mendeliome v0.3323 | EXOC2 |
Zornitza Stark gene: EXOC2 was added gene: EXOC2 was added to Mendeliome. Sources: Expert Review Mode of inheritance for gene: EXOC2 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: EXOC2 were set to 32639540 Phenotypes for gene: EXOC2 were set to Global developmental delay; Intellectual disability; Abnormality of the face; Abnormality of brain morphology Review for gene: EXOC2 was set to AMBER Added comment: Van Bergen et al (2020 - PMID: 32639540) report on 3 individuals from 2 families, harboring biallelic EXOC2 mutations. Clinical presentation included DD, ID (severe in 2 subjects from fam1, borderline intellectual functioning in fam2), dysmorphic features and brain abnormalities. Cerebellar anomalies were common to all with a molar tooth sign observed in one (1/3). Other findings limited to subjects from one family included acquired microcephaly, congenital contractures, spastic quadriplegia (each observed 2/3). Previous investigations were in all cases non-diagnostic. WES identified biallelic EXOC2 mutations in all affected individuals. EXOC2 encodes an exocyst subunit. The latter is an octameric complex, component of the membrane transport machinery, required for tethering and fusion of vesicles at the plasma membrane. As discussed ,vesicle transport is important for the development of brain and the function of neurons and glia. Exocyst function is also important for delivery of Arl13b to the primary cilium (biallelic ARL13B mutations cause Joubert syndrome 8) and ciliogenesis. Affected subjects from a broader consanguineous family (fam1) were homozygous for a truncating variant. Fibroblast studies revealed mRNA levels compatible with NMD (further restored in presence of CHX) as well as reduced protein levels. The female belonging to the second non-consanguineous family was found to harbor 2 missense variants in trans configuration. An exocytosis defect was demonstrated in fibroblasts from individuals belonging to both families. Ciliogenesis appeared to be normal, however Arl13b localization/recruitment to the cilia was reduced compared with control cells with the defect rescued upon exogenous expression of wt EXOC2. Mutations in other genes encoding components of the exocyst complex have been previously reported in individuals with relevant phenotypes (e.g. EXOC8 in a boy with features of Joubert s. or EXOC4 in nephrotic syndrome). The authors discuss on the essential role of EXOC2 based on model organism studies (e.g. impaired neuronal membrane traffic, failure of neuronal polarization and neuromuscular junction expansion seen in Drosophila Sec5 (EXOC2) null mutants). Sources: Expert Review |
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| Mendeliome v0.1850 | FBN2 | Zornitza Stark Added comment: Comment when marking as ready: The gene-disease association with Contractual arachnodactyly is extremely well established. The gene-disease association with macular degeneration much less so. There are ~4 families reported in the literature, and some discussion about whether the contribution of rare FBN2 variants in this context are under a 'monogenic' or 'polygenic' model. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mendeliome v0.1673 | KANK1 | Zornitza Stark changed review comment from: Comment on list classification: Amber for nephrotic after discussion with Chirag Patel.; to: Comment on list classification: Red for nephrotic after discussion with Chirag Patel. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mendeliome v0.374 | KANK1 | Zornitza Stark Added comment: Comment on list classification: Amber for nephrotic after discussion with Chirag Patel. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mendeliome v0.0 | ISCU |
Zornitza Stark gene: ISCU was added gene: ISCU was added to Mendeliome_VCGS. Sources: Expert Review Green,Victorian Clinical Genetics Services Mode of inheritance for gene: ISCU was set to Unknown |
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