PanelApp

Activity

Filter

Cancel
Date Panel Item Activity
41 actions
Intellectual disability syndromic and non-syndromic v0.6734 GNPAT Zornitza Stark Phenotypes for gene: GNPAT were changed from to glyceronephosphate O-acyltransferase deficiency MONDO:0100273
Intellectual disability syndromic and non-syndromic v0.6418 MAT1A Zornitza Stark Phenotypes for gene: MAT1A were changed from to Hypermethioninemia, persistent, autosomal dominant, due to methionine adenosyltransferase I/III deficiency MIM#250850; Methionine adenosyltransferase deficiency, autosomal recessive MIM#250850; Disorders of the metabolism of sulphur amino acids
Intellectual disability syndromic and non-syndromic v0.6303 MAT1A Chirag Patel reviewed gene: MAT1A: Rating: GREEN; Mode of pathogenicity: None; Publications: PMID: 27604308, 7560086; Phenotypes: Hypermethioninemia, persistent, autosomal dominant, due to methionine adenosyltransferase I/III deficiency MIM#250850, Methionine adenosyltransferase deficiency, autosomal recessive MIM#250850, Disorders of the metabolism of sulphur amino acids; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability syndromic and non-syndromic v0.6295 GAMT Bryony Thompson Phenotypes for gene: GAMT were changed from to guanidinoacetate methyltransferase deficiency MONDO:0012999
Intellectual disability syndromic and non-syndromic v0.6292 GAMT Bryony Thompson reviewed gene: GAMT: Rating: GREEN; Mode of pathogenicity: None; Publications: 20301745; Phenotypes: guanidinoacetate methyltransferase deficiency MONDO:0012999; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability syndromic and non-syndromic v0.6222 GNPAT Sangavi Sivagnanasundram reviewed gene: GNPAT: Rating: GREEN; Mode of pathogenicity: None; Publications: 9843043, 19270340, 21990100; Phenotypes: glyceronephosphate O-acyltransferase deficiency MONDO:0100273; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability syndromic and non-syndromic v0.6195 EIF3I Mark Cleghorn gene: EIF3I was added
gene: EIF3I was added to Intellectual disability syndromic and non-syndromic. Sources: Other
Mode of inheritance for gene: EIF3I was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Phenotypes for gene: EIF3I were set to complex neurodevelopmental disorder MONDO:0100038
Penetrance for gene: EIF3I were set to unknown
Review for gene: EIF3I was set to AMBER
Added comment: Marcello Scala, Genoa
ESHG presentation 4/6/24, unpublished

De novo EIF3I missense variants as a cause for novel NDD syndrome

EIF3 complex involved in regulating initiation of mRNA translation
Negative regulator of the TGF beta pathway

8 individuals from 8 families
Mod/severe GDD or ID
Short stature
Midline brain anomalies (hypoplasia/agenesis of corpus callosum and pituitary hypoplasia)
Frontal bossing, hypertelorism, long philtrum
All w rare de novo missense variants om EIF3I, clustering within highly conserved WD repeats

Functional studies
Transfected HEK293 cell studies suggested EIF3I protein from variant alleles (from patients above) had disrupted interaction with other EIF subunits, and cells had reduced protein synthesis overall
No animal models
Sources: Other
Intellectual disability syndromic and non-syndromic v0.6188 MED16 Mark Cleghorn gene: MED16 was added
gene: MED16 was added to Intellectual disability syndromic and non-syndromic. Sources: Other
Mode of inheritance for gene: MED16 was set to BIALLELIC, autosomal or pseudoautosomal
Phenotypes for gene: MED16 were set to complex neurodevelopmental disorder MONDO:0100038
Penetrance for gene: MED16 were set to unknown
Review for gene: MED16 was set to GREEN
Added comment: MED16
Charlotte Guillouet, Imagine institute Paris
ESHG presentation 4/6/24, unpublished

MED16 is part of tail of ‘mediator complex’
Plays a role in enhancer/promotor regions

Disruptive variants in other genes encoding proteins within this mediator complex (MED11/12/12/17/20, CDK8) are assoc w neurodevelopmental/neurodegenerative disorders

Cases
index family
Sibs (M/F) to consanguineous parents w NDD/mod ID, tetralogy of Fallot or VSD, bilat deafness, micrognathia, malar hypoplasia, dental AbN, pre auricular tags, hypoplastic nails, brachydactly
WES: biallelic MED16 p.Asp217Asn

Via genematcher
16 families total, 22 individuals, homozygous or compound het rare MED16 variants
Mixture of pLoF and missense variants

Motor delay in 16/17
DD or ID in 17/17
Speech delay in 15/15
6/19 ToF
7/19 other septal/aortic defects
6/18 deafness
11/18 microretognathia
6/17 cleft palate
8/19 preauricular tags
9/20 puffy eyelids
12/20 nasal dysplasia (most commonly short columella w bulbous nasal tip)
7/20 corpus callosum anomalies

Not clear that functional work recapitulated phenotype as yet?
Immunofluroescence on HeLa cells transfected with variants observed ?conclusion
MED16 knockout mouse > growth delay, pre weaning lethality
MED16 knockout zebrafish > reduced body length, early death, no obvious craniofacial phenotype
Sources: Other
Intellectual disability syndromic and non-syndromic v0.5786 PRMT9 Chirag Patel gene: PRMT9 was added
gene: PRMT9 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature
Mode of inheritance for gene: PRMT9 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PRMT9 were set to PMID: 38561334
Phenotypes for gene: PRMT9 were set to Neurodevelopmental disorder, MONDO:0100500
Review for gene: PRMT9 was set to RED
Added comment: A homozygous variant (G189R) in PRMT9 is reported based on large WGS study in 136 consanguineous families - unclear if only found in 1 family and no clinical information on case(s).

PMRTs (protein arginine methyltransferases) catalyse post translational modification via arginine methylation. Functional studies showed that the G189R variant abolishes PRMT9's methyltransferase activity - specifically at the R508 residue of SF3B2 RNA (exclusively methylated by PRMT9) - and leads to heavy PRMT9 ubiquitination, and abnormal splicing activity of SF3B2. Knock out mouse model showed PRMT9 loss in excitatory neurons leads to aberrant synapse development and impaired learning and memory.
Sources: Literature
Intellectual disability syndromic and non-syndromic v0.5397 FTCD Bryony Thompson Phenotypes for gene: FTCD were changed from to Glutamate formiminotransferase deficiency MIM#229100
Intellectual disability syndromic and non-syndromic v0.5390 COL4A3BP Ee Ming Wong changed review comment from: - Thirty-one unrelated individuals with twenty-two distinct missense variants. The majority of variants were de novo.
- Several variants transfected into HeLa cells demonstrated gain of CERT activity
- CERT gain of function in Drosophila melanogaster led to head and brain size defects and impaired locomotor activity, which was corrected by pharmacological inhibition of CERT; to: - current HGNC symbol: CERT1
- Thirty-one unrelated individuals with twenty-two distinct missense variants. The majority of variants were de novo.
- Several variants transfected into HeLa cells demonstrated gain of CERT activity
- CERT gain of function in Drosophila melanogaster led to head and brain size defects and impaired locomotor activity, which was corrected by pharmacological inhibition of CERT
Intellectual disability syndromic and non-syndromic v0.5390 COL4A3BP Ee Ming Wong changed review comment from: - Thirty-one unrelated individuals with twenty-two distinct missense variants. The majority of variants were de novo.
- Several variants transfected into HeLa cells demonstrated gain of CERT activity
- CERT gain of function in Drosophila melanogaster led to head and brain size defects and impaired locomotor activity,
which was corrected by pharmacological inhibition of CERT; to: - Thirty-one unrelated individuals with twenty-two distinct missense variants. The majority of variants were de novo.
- Several variants transfected into HeLa cells demonstrated gain of CERT activity
- CERT gain of function in Drosophila melanogaster led to head and brain size defects and impaired locomotor activity, which was corrected by pharmacological inhibition of CERT
Intellectual disability syndromic and non-syndromic v0.5390 COL4A3BP Ee Ming Wong changed review comment from: - Thirty-one unrelated individuals with twenty-two distinct missense variants. The majority of variants were de novo.
- Several variants transfected into HeLa cells demonstrated gain of CERT activity
- CERT gain of function in Drosophila melanogaster led to head and brain size defects and impaired locomotor activity,
which was corrected by pharmacological inhibition of CERT; to: - Thirty-one unrelated individuals with twenty-two distinct missense variants. The majority of variants were de novo.
- Several variants transfected into HeLa cells demonstrated gain of CERT activity
- CERT gain of function in Drosophila melanogaster led to head and brain size defects and impaired locomotor activity,
which was corrected by pharmacological inhibition of CERT
Intellectual disability syndromic and non-syndromic v0.5313 GPRC5B Lucy Spencer gene: GPRC5B was added
gene: GPRC5B was added to Intellectual disability syndromic and non-syndromic. Sources: Literature
Mode of inheritance for gene: GPRC5B was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: GPRC5B were set to PMID: 37143309
Phenotypes for gene: GPRC5B were set to Megalencephalic leukoencephalopathy with subcortical cysts 3 MIM#620447
Review for gene: GPRC5B was set to GREEN
Added comment: PMID: 37143309
Cohort of 5 patients with an MRI based diagnosis of megalencephalic leukoencephalopathy with subcortical cysts (MLC). 3 unrelated patients had variants in GPRC5B, 2 have the same inframe dup Ile175dup and the third has an in frame dup of Ala177. All 3 were de novo and unaffected siblings did not have the variants. All patients have macrocephaly, delayed motor development, spasticity, ataxia and dystonia, seizures, all had varying degrees of cognitive deficits. MRI showed MLC, abnormal and swollen cerebral white matter.

Patient cell lines showed reduced regulatory volume decrease, and western blot showed a strong increase in GRPC5B levels in patient lymphoblasts. Together, these findings indicate disturbed volume regulation in lymphoblasts from patients with GPRC5B variants, potentially due to increased GPRC5B levels. Transfected cells caused increased volume-regulated anion channel activity.
Sources: Literature
Intellectual disability syndromic and non-syndromic v0.5311 NAA30 Sarah Pantaleo gene: NAA30 was added
gene: NAA30 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature
Mode of inheritance for gene: NAA30 was set to Unknown
Publications for gene: NAA30 were set to PMID: 37387332
Penetrance for gene: NAA30 were set to unknown
Review for gene: NAA30 was set to RED
Added comment: Report a de novo heterozygous NAA30 nonsense variant c.244C>T, p.(Gln82*) in a 5yo boy with GDD, ASD, hypotonia, seizures, tracheal cleft and recurrent respiratory infections. Seizures resolved after two weeks of life. Family history of ASD in older sister. Epilepsy in mother, childhood onset.

Biochemical studies performed to assess the functional impact of the premature stop codon on catalytic activity. The variant was found to completely disrupt N-terminal acetyltransferase activity using an in vitro acetylation assay.

Variant de novo, “in a gene sensitive to loss of heterozygosity”. Limitation of study - have not established whether this gene variant acts in a dominant or recessive manner.
Sources: Literature
Intellectual disability syndromic and non-syndromic v0.4775 PROSER1 Chirag Patel gene: PROSER1 was added
gene: PROSER1 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature
Mode of inheritance for gene: PROSER1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PROSER1 were set to PMID: 35229282
Phenotypes for gene: PROSER1 were set to Developmental delay, hypotonia, seizures, failure-to-thrive, strabismus, drooling, recurrent otitis media, hearing impairment, and genitourinary malformations, no OMIM #
Review for gene: PROSER1 was set to RED
Added comment: 4 children from 3 related families with developmental delay, hypotonia, seizures, failure-to-thrive, strabismus, drooling, recurrent otitis media, hearing impairment, genitourinary malformations, and common facial features (arched eyebrows, prominent eyes, broad nasal bridge, low-hanging columella, open mouth, thick lower lip, protruding tongue, large low-set ears, and parietal bossing). WES revealed a homozygous frame-shift variant (p.Thr612Glnfs*22) in PROSER1. This encodes the proline and serine rich protein 1, part of the histone methyltransferases KMT2C/KMT2D complexes. PROSER1 stabilizes TET2, a member of the TET family of DNA demethylases which is involved in recruiting the enhancer-associated KMT2C/KMT2D complexes and mediating DNA demethylation, activating gene expression. Therefore, PROSER1 may play vital and potentially general roles in gene regulation. No functional assays and 3 related families.
Sources: Literature
Intellectual disability syndromic and non-syndromic v0.4662 PIGA Zornitza Stark edited their review of gene: PIGA: Added comment: PMID 34875027: variants in PIGA causing a neurodevelopment disorder and a juvenile form of hereditary hemochromatosis reported in > three unrelated patients. All patients had increased serum iron, ferritin and transferrin saturation levels, high ALP and low hepcidin. All patients had generalised seizures and intellectual disability. A subpopulation of patient blood cells showed a slight reduction of GPI-anchored proteins, suggesting that the mutations were hypomorphic and retained some residual activity. CRISPR/Cas12a-mediated knockdown of PIGA in Hep3B liver cells eliminated the cell surface expression of GPI-anchored proteins CD59 and hemojuvelin (HJV; 608374), as well as caused decreased expression of hepcidin (606464) compared to controls. These hypomorphic alleles could explain the milder neurologic phenotype, which allowed for sufficiently long survival for the iron overload phenotype to manifest.; Changed publications: 22305531, 24357517, 24706016, 26545172, 33333793, 32694024, 34875027; Changed phenotypes: Multiple congenital anomalies-hypotonia-seizures syndrome 2, MIM# 300868, MONDO:0010466, Neurodevelopmental disorder with epilepsy and haemochromatosis, MIM# 301072
Intellectual disability syndromic and non-syndromic v0.4658 TRAPPC10 Naomi Baker gene: TRAPPC10 was added
gene: TRAPPC10 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature
Mode of inheritance for gene: TRAPPC10 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TRAPPC10 were set to PMID: 35298461; 30167849
Phenotypes for gene: TRAPPC10 were set to neurodevelopmental disorder (MONDO:0700092), TRAPPC10-related
Review for gene: TRAPPC10 was set to GREEN
Added comment: PMID: 35298461 – two Pakistani families reported with homozygous variants. Family 1 has frameshift variant in 8 affected individual and family 2 has missense variant in 2 affected individuals. Patients present with microcephaly, short stature, hypotonia, severe ID and behavioural abnormalities. Seizures also reported in 4/10 individuals. Paper also reported brain abnormalities in null mouse model and other functional in transfected cell lines.

PMID: 30167849 – initial report of family 2 above.
Sources: Literature
Intellectual disability syndromic and non-syndromic v0.4408 NAA20 Chirag Patel gene: NAA20 was added
gene: NAA20 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature
Mode of inheritance for gene: NAA20 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: NAA20 were set to PMID: 34230638
Phenotypes for gene: NAA20 were set to Autosomal recessive developmental delay, intellectual disability, and microcephaly
Added comment: 2 consanguineous families with 5 affected individuals with developmental delay, intellectual disability, and microcephaly (-2-4SD). Exome and genome sequencing identified 2 different homozygous variants in NAA20 gene (p.Met54Val and p.Ala80Val), and segregated with affected individuals. N-terminal acetyltransferases modify proteins by adding an acetyl moiety to the first amino acid and are vital for protein and cell function. The NatB complex acetylates 20% of the human proteome and is composed of the catalytic subunit NAA20 and the auxiliary subunit NAA25. Both NAA20-M54V and NAA20-A80V were impaired in their capacity to form a NatB complex with NAA25, and in vitro acetylation assays revealed reduced catalytic activities toward different NatB substrates.
Sources: Literature
Intellectual disability syndromic and non-syndromic v0.4059 RNF220 Konstantinos Varvagiannis changed review comment from: Sferra et al (2021 - PMID: 33964137) provide extensive evidence that biallelic RNF220 mutations cause a disorder characterized by hypomyelinating leukodystrophy, ataxia (9/9 - onset 1-5y), borderline intellectual functioning (3/9) / intellectual disability (5/9 - in most cases mild), sensorineural deafness (9/9) with complete hearing loss in the first decade of life, hepatopathy (9/9) with associated periportal fibrosis, and dilated cardiomyopathy (9/9) which was fatal.

Other neurologic manifestations apart from ataxia incl. hyperreflexia (8/8), spastic paraplegia (9/9), dysarthria (9/9), peripheral neuropathy (4/9), seizures in one case (1/9). Upon brain MRI there was thin corpus callosum (9/9) or cerebellar atrophy in some (2/9).

The authors identified homozygosity for 2 recurrent missense RNF220 variants in affected members belonging to these 5 broad consanguineous pedigrees (7 families), namely NM_018150.4:c.1094G>A / p.Arg365Gly in 4 Roma families in the context of a shared haplotype (/founder effect) as well as c.1088G>A / p.Arg363Gly in a large pedigree from southern Italy initially reported by Leuzzi et al (2000 - PMID: 10881263).

Extensive segregation analyses were carried out including several affected and unaffected members.

RNF220 encodes ring finger protein 220, which functions as an E3 ubiquitin ligase. Previous studies have shown among others a role in modulation of Sonic hedgehog/GLI signaling and cerebellar development

Evidence for the role of RNF220 included relevant expression, localization within the cell, interaction partners (lamin B1, 20S proteasome), similarities with other laminopathies in terms of phenotype, etc :
*RNF220 has a relevant expression pattern in CNS (based on qRT-PCR analyses in human brain, cerebellum, cerebral cortex / mRNA levels in human fetal CNS with higher expression in cerebellum, spinal cord and cortex / previous GTEx data / protein levels in mouse CNS)
*The protein displays nuclear localization based on iPSC cells differentiated to motor neurons (also supported by data from the Human Protein Atlas). Transfection of COS-1 cells demonstrated localization primarily to the nucleus (as also previously demonstrated in HEK293T cells) in vesicle like structures with ASF2/SF2 colocalization suggesting enrichment in nuclear speckles. There was also partial co-distribution with the 20S proteasome. R363Q and R365Q additionally coalesced in the cytoplasm forming protein aggregates/inclusions.
*Immunofluorescence studies in patient fibroblasts also confirmed abnormal increase of the protein in the cytoplasm and increased fluorescence with the 20S proteasome.
*Proteomic identification of RNF220-interacting proteins in transfected HEK293T cells demonstrated enrichment for all members of the lamin protein family (incl . lamin B1, AC, B2).
*RNAi-mediated downregulation of RNF222 in Drosophila suggested altered subcellular localization and accumulation of the fly orthologue for human lamin B1.
*Immunoprecipitation of lamin B1 from the nuclear matrix of cerebellar cells suggested significant interaction of endogenous lamin B1 with RNF220, while transfection studies in HEK293T cells for wt/mt suggested reduced binding to endogenous lamin B1 for RNF220 mt compared to wt (more prominent for R365Q). RNF220 mutants also reduced ubiquitination of nuclear lamin B1 compared to wt.
*Patient fibroblasts immunostained with different nuclear envelope markers displayed abnormal nuclear shapes with multiple invaginations and lobulations, findings also observed in laminopathies.

There is currently no associated phenotype in OMIM or G2P. SysID includes RNF220 among the current primary ID genes.
Sources: Literature, Other; to: Sferra et al (2021 - PMID: 33964137) provide extensive evidence that biallelic RNF220 mutations cause a disorder characterized by hypomyelinating leukodystrophy, ataxia (9/9 - onset 1-5y), borderline intellectual functioning (3/9) / intellectual disability (5/9 - in most cases mild), sensorineural deafness (9/9) with complete hearing loss in the first decade of life, hepatopathy (9/9) with associated periportal fibrosis, and dilated cardiomyopathy (9/9) which was fatal.

Other neurologic manifestations apart from ataxia incl. hyperreflexia (8/8), spastic paraplegia (9/9), dysarthria (9/9), peripheral neuropathy (4/9), seizures in one case (1/9). Upon brain MRI there was thin corpus callosum (9/9) or cerebellar atrophy in some (2/9).

The authors identified homozygosity for 2 recurrent missense RNF220 variants in affected members belonging to these 5 broad consanguineous pedigrees (7 families), namely NM_018150.4:c.1094G>A / p.Arg365Gly in 4 Roma families in the context of a shared haplotype (/founder effect) as well as c.1088G>A / p.Arg363Gly in a large pedigree from southern Italy initially reported by Leuzzi et al (2000 - PMID: 10881263).

Extensive segregation analyses were carried out including several affected and unaffected members.

RNF220 encodes ring finger protein 220, which functions as an E3 ubiquitin ligase. Previous studies have shown among others a role in modulation of Sonic hedgehog/GLI signaling and cerebellar development

Evidence for the role of RNF220 included relevant expression, localization within the cell, interaction partners (lamin B1, 20S proteasome), similarities with other laminopathies in terms of phenotype, etc :
*RNF220 has a relevant expression pattern in CNS (based on qRT-PCR analyses in human brain, cerebellum, cerebral cortex / mRNA levels in human fetal CNS with higher expression in cerebellum, spinal cord and cortex / previous GTEx data / protein levels in mouse CNS)
*The protein displays nuclear localization based on iPSC cells differentiated to motor neurons (also supported by data from the Human Protein Atlas). Transfection of COS-1 cells demonstrated localization primarily to the nucleus (as also previously demonstrated in HEK293T cells) in vesicle like structures with ASF2/SF2 colocalization suggesting enrichment in nuclear speckles. There was also partial co-distribution with the 20S proteasome. R363Q and R365Q additionally coalesced in the cytoplasm forming protein aggregates/inclusions.
*Immunofluorescence studies in patient fibroblasts also confirmed abnormal increase of the protein in the cytoplasm and increased fluorescence with the 20S proteasome.
*Proteomic identification of RNF220-interacting proteins in transfected HEK293T cells demonstrated enrichment for all members of the lamin protein family (incl . lamin B1, AC, B2).
*RNAi-mediated downregulation of RNF222 in Drosophila suggested altered subcellular localization and accumulation of the fly orthologue for human lamin B1.
*Immunoprecipitation of lamin B1 from the nuclear matrix of cerebellar cells suggested significant interaction of endogenous lamin B1 with RNF220, while transfection studies in HEK293T cells for wt/mt suggested reduced binding to endogenous lamin B1 for RNF220 mt compared to wt (more prominent for R365Q). RNF220 mutants also reduced ubiquitination of nuclear lamin B1 compared to wt.
*Patient fibroblasts immunostained with different nuclear envelope markers displayed abnormal nuclear shapes with multiple invaginations and lobulations, findings also observed in laminopathies.

There is currently no associated phenotype in OMIM or G2P. SysID includes RNF220 among the current primary ID genes.

Consider inclusion in panels for leukodystrophies, childhood onset ataxia, sensorineural hearing loss, corpus callosum anomalies, cardiomyopathies, hepatopathies, etc in all cases with green rating.

Sources: Literature, Other
Intellectual disability syndromic and non-syndromic v0.4059 RNF220 Konstantinos Varvagiannis gene: RNF220 was added
gene: RNF220 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature,Other
Mode of inheritance for gene: RNF220 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: RNF220 were set to 33964137; 10881263
Phenotypes for gene: RNF220 were set to Leukodystrophy; CNS hypomyelination; Ataxia; Intellectual disability; Sensorineural hearing impairment; Elevated hepatic transaminases; Hepatic fibrosis; Dilated cardiomyopathy; Spastic paraplegia; Dysarthria; Abnormality of the corpus callosum
Penetrance for gene: RNF220 were set to Complete
Review for gene: RNF220 was set to GREEN
Added comment: Sferra et al (2021 - PMID: 33964137) provide extensive evidence that biallelic RNF220 mutations cause a disorder characterized by hypomyelinating leukodystrophy, ataxia (9/9 - onset 1-5y), borderline intellectual functioning (3/9) / intellectual disability (5/9 - in most cases mild), sensorineural deafness (9/9) with complete hearing loss in the first decade of life, hepatopathy (9/9) with associated periportal fibrosis, and dilated cardiomyopathy (9/9) which was fatal.

Other neurologic manifestations apart from ataxia incl. hyperreflexia (8/8), spastic paraplegia (9/9), dysarthria (9/9), peripheral neuropathy (4/9), seizures in one case (1/9). Upon brain MRI there was thin corpus callosum (9/9) or cerebellar atrophy in some (2/9).

The authors identified homozygosity for 2 recurrent missense RNF220 variants in affected members belonging to these 5 broad consanguineous pedigrees (7 families), namely NM_018150.4:c.1094G>A / p.Arg365Gly in 4 Roma families in the context of a shared haplotype (/founder effect) as well as c.1088G>A / p.Arg363Gly in a large pedigree from southern Italy initially reported by Leuzzi et al (2000 - PMID: 10881263).

Extensive segregation analyses were carried out including several affected and unaffected members.

RNF220 encodes ring finger protein 220, which functions as an E3 ubiquitin ligase. Previous studies have shown among others a role in modulation of Sonic hedgehog/GLI signaling and cerebellar development

Evidence for the role of RNF220 included relevant expression, localization within the cell, interaction partners (lamin B1, 20S proteasome), similarities with other laminopathies in terms of phenotype, etc :
*RNF220 has a relevant expression pattern in CNS (based on qRT-PCR analyses in human brain, cerebellum, cerebral cortex / mRNA levels in human fetal CNS with higher expression in cerebellum, spinal cord and cortex / previous GTEx data / protein levels in mouse CNS)
*The protein displays nuclear localization based on iPSC cells differentiated to motor neurons (also supported by data from the Human Protein Atlas). Transfection of COS-1 cells demonstrated localization primarily to the nucleus (as also previously demonstrated in HEK293T cells) in vesicle like structures with ASF2/SF2 colocalization suggesting enrichment in nuclear speckles. There was also partial co-distribution with the 20S proteasome. R363Q and R365Q additionally coalesced in the cytoplasm forming protein aggregates/inclusions.
*Immunofluorescence studies in patient fibroblasts also confirmed abnormal increase of the protein in the cytoplasm and increased fluorescence with the 20S proteasome.
*Proteomic identification of RNF220-interacting proteins in transfected HEK293T cells demonstrated enrichment for all members of the lamin protein family (incl . lamin B1, AC, B2).
*RNAi-mediated downregulation of RNF222 in Drosophila suggested altered subcellular localization and accumulation of the fly orthologue for human lamin B1.
*Immunoprecipitation of lamin B1 from the nuclear matrix of cerebellar cells suggested significant interaction of endogenous lamin B1 with RNF220, while transfection studies in HEK293T cells for wt/mt suggested reduced binding to endogenous lamin B1 for RNF220 mt compared to wt (more prominent for R365Q). RNF220 mutants also reduced ubiquitination of nuclear lamin B1 compared to wt.
*Patient fibroblasts immunostained with different nuclear envelope markers displayed abnormal nuclear shapes with multiple invaginations and lobulations, findings also observed in laminopathies.

There is currently no associated phenotype in OMIM or G2P. SysID includes RNF220 among the current primary ID genes.
Sources: Literature, Other
Intellectual disability syndromic and non-syndromic v0.4051 VPS50 Konstantinos Varvagiannis gene: VPS50 was added
gene: VPS50 was added to Intellectual disability syndromic and non-syndromic. 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
Penetrance for gene: VPS50 were set to Complete
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.

Consider inclusion in other relevant gene panels (e.g. for neonatal cholestasis, epilepsy, microcephaly, growth failure in early infancy, corpus callosum anomalies, etc) with amber rating pending further reports.
Sources: Literature
Intellectual disability syndromic and non-syndromic v0.3930 FTCD Elena Savva reviewed gene: FTCD: Rating: AMBER; Mode of pathogenicity: None; Publications: PMID: 29178637, 30740726; Phenotypes: Glutamate formiminotransferase deficiency MIM#229100; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability syndromic and non-syndromic v0.3862 FARSA Chirag Patel gene: FARSA was added
gene: FARSA was added to Intellectual disability syndromic and non-syndromic. Sources: Literature
Mode of inheritance for gene: FARSA was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: FARSA were set to PMID: 33598926
Phenotypes for gene: FARSA were set to Rajab interstitial lung disease with brain calcifications 2
Review for gene: FARSA was set to GREEN
gene: FARSA was marked as current diagnostic
Added comment: FARSA is a subunit with FARSB to form FARS1 enzyme. Bi-allelic mutations in FARSB are well described.
Schuch et al. (2021) report 3 unrelated individuals with bi-allelic variants in FARSA. Identified through WES and variants segregated with disease. Functional evidence was obtained with reduced FARS1 enzyme activity levels in fibroblasts or EBV-transformed lymphoblastoid cell lines (EBV-LCLs) of patients. Common to all was a chronic interstitial lung disease starting early in life and characterized by bilateral ground-glass opacification on HR-CT, and cholesterol pneumonitis in lung histology. Additional abnormalities in other organ systems include liver disease, neurological manifestations, and growth restriction.
Sources: Literature
Intellectual disability syndromic and non-syndromic v0.3799 NSF Zornitza Stark Phenotypes for gene: NSF were changed from Seizures; EEG with burst suppression; Global developmental delay; Intellectual disability to Developmental and epileptic encephalopathy 96, MIM# 619340; Seizures; EEG with burst suppression; Global developmental delay; Intellectual disability
Intellectual disability syndromic and non-syndromic v0.3798 NSF Zornitza Stark edited their review of gene: NSF: Changed phenotypes: Developmental and epileptic encephalopathy 96, MIM# 619340, Seizures, EEG with burst suppression, Global developmental delay, Intellectual disability
Intellectual disability syndromic and non-syndromic v0.3328 ST3GAL5 Zornitza Stark Phenotypes for gene: ST3GAL5 were changed from Salt and pepper developmental regression syndrome; OMIM #609056 to Salt and pepper developmental regression syndrome 609056; GM3 synthase deficiency, MONDO:0018274; Lactosylceramide alpha-2,3-sialyltransferase deficiency (Disorders of glycosphingolipid and glycosylphosphatidylinositol anchor glycosylation)
Intellectual disability syndromic and non-syndromic v0.3326 ST3GAL5 Zornitza Stark reviewed gene: ST3GAL5: Rating: GREEN; Mode of pathogenicity: None; Publications: 23436467, 22990144, 15502825, 27232954, 30691927, 30688114, 30576498; Phenotypes: Salt and pepper developmental regression syndrome 609056, GM3 synthase deficiency, MONDO:0018274, Lactosylceramide alpha-2,3-sialyltransferase deficiency (Disorders of glycosphingolipid and glycosylphosphatidylinositol anchor glycosylation); Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability syndromic and non-syndromic v0.3062 SHMT2 Konstantinos Varvagiannis gene: SHMT2 was added
gene: SHMT2 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature
Mode of inheritance for gene: SHMT2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: SHMT2 were set to 33015733
Phenotypes for gene: SHMT2 were set to Congenital microcephaly; Infantile axial hypotonia; Spastic paraparesis; Global developmental delay; Intellectual disability; Abnormality of the corpus callosum; Abnormal cortical gyration; Hypertrophic cardiomyopathy; Abnormality of the face; Proximal placement of thumb; 2-3 toe syndactyly
Penetrance for gene: SHMT2 were set to Complete
Review for gene: SHMT2 was set to GREEN
Added comment: García‑Cazorla et al. (2020 - PMID: 33015733) report 5 individuals (from 4 families) with a novel brain and heart developmental syndrome caused by biallelic SHMT2 pathogenic variants.

All affected subjects presented similar phenotype incl. microcephaly at birth (5/5 with OFC < -2 SD though in 2/5 cases N OFC was observed later), DD and ID (1/5 mild-moderate, 1/5 moderate, 3/5 severe), motor dysfunction in the form of spastic (5/5) paraparesis, ataxia/dysmetria (3/4), intention tremor (in 3/?) and/or peripheral neuropathy (2 sibs). They exhibited corpus callosum hypoplasia (5/5) and perisylvian microgyria-like pattern (4/5). Cardiac problems were reported in all, with hypertrophic cardiomyopathy in 4/5 (from 3 families) and atrial-SD in the 5th individual (1/5). Common dysmorphic features incl. long palpebral/fissures, eversion of lateral third of lower eylids, arched eyebrows, long eyelashes, thin upper lip, short Vth finger, fetal pads, mild 2-3 toe syndactyly, proximally placed thumbs.

Biallelic variants were identified following exome sequencing in all (other investigations not mentioned). Identified variants were in all cases missense SNVs or in-frame del, which together with evidence from population databases and mouse model might suggest a hypomorphic effect of variants and intolerance/embryonic lethality for homozygous LoF ones.

SHMT2 encodes the mitohondrial form of serine hydroxymethyltransferase. The enzyme transfers one-carbon units from serine to tetrahydrofolate (THF) and generates glycine and 5,10,methylene-THF.

Mitochondrial defect was suggested by presence of ragged red fibers in myocardial biopsy of one patient. Quadriceps and myocardial biopsies of the same individual were overall suggestive of myopathic changes.

While plasma metabolites were within N range and SHMT2 protein levels not significantly altered in patient fibroblasts, the authors provide evidence for impaired enzymatic function eg. presence of the SHMT2 substrate (THF) in patient but not control (mitochondria-enriched) fibroblasts , decrease in glycine/serine ratios, impared folate metabolism. Patient fibroblasts displayed impaired oxidative capacity (reduced ATP levels in a medium without glucose, diminished oxygen consumption rates). Mitochondrial membrane potential and ROS levels were also suggestive of redox malfunction.

Shmt2 ko in mice was previously shown to be embryonically lethal attributed to severe mitochondrial respiration defects, although there was no observed brain metabolic defect.

The authors performed Shmt2 knockdown in motoneurons in Drosophila, demonstrating neuromuscular junction (# of satellite boutons) and motility defects (climbing distance/velocity).

Overall this gene can be considered for inclusion with (probably) green rating in gene panels for ID, metabolic / mitochondrial disorders, cardiomyopathy, congenital microcephaly, corpus callosum anomalies, etc.
Sources: Literature
Intellectual disability syndromic and non-syndromic v0.2833 FAM50A Konstantinos Varvagiannis gene: FAM50A was added
gene: FAM50A was added to Intellectual disability syndromic and non-syndromic. Sources: Literature
Mode of inheritance for gene: FAM50A was set to X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males)
Publications for gene: FAM50A were set to 32703943
Phenotypes for gene: FAM50A were set to Mental retardation syndrome, X-linked, Armfield type (MIM #300261)
Penetrance for gene: FAM50A were set to unknown
Review for gene: FAM50A was set to GREEN
Added comment: Lee et al (2020 - PMID: 32703943) provide evidence that Armfield X-Linked intellectual disability syndrome is caused by monoallelic FAM50A pathogenic variants. The current review is based only on this reference.

The authors provide clinical details on 6 affected individuals from 5 families.

Features included postnatal growth delay, DD and ID (6/6 - also evident for those without formal IQ assesment), seizures (3/6 from 2 families), prominent forehead with presence of other facial features and variable head circumference (5th to >97th %le), ocular anomalies (5/6 - strabismus/nystagmus/Axenfeld-Rieger), cardiac (3/6 - ASD/Fallot) and genitourinary anomalies (3/6).

In the first of these families (Armfield et al 1999 - PMID: 10398235), linkage analysis followed by additional studies (Sanger, NGS of 718 genes on chrX, X-exome NGS - several refs provided) allowed the identification of a FAM50A variant. Variants in other families were identified by singleton (1 fam) or trio-ES (3 fam).

In affected individuals from 3 families, the variant had occurred de novo. Carrier females in the other families were unaffected (based on pedigrees and/or the original publication). XCI was rather biased in most obligate carrier females from the 1st family (although this ranged from 95:5 to 60:40).

Missense variants were reported in all affected subjects incl. Trp206Gly, Asp255Gly, Asp255Asn (dn), Glu254Gly (dn), Arg273Trp (dn) (NM_004699.3).

Previous studies have demonstrated that FAM50A has ubiquitous expression in human fetal and adult tissues (incl. brain in fetal ones).

Immunostaining suggests a nuclear localization for the protein (NIH/3T3 cells). Comparison of protein levels in LCLs from affected males and controls did not demonstrate significant differences. Protein localization for 3 variants (transfection of COS-7 cells) was shown to be similar to wt.

Complementation studies in zebrafish provided evidence that the identified variants confer partial loss of function (rescue of the morpholino phenotype with co-injection of wt but not mt mRNA). The zebrafish ko model seemed to recapitulate the abnormal development of cephalic structures and was indicative of diminished/defective neurogenesis. Transcriptional dysregulation was demonstrated in zebrafish (altered levels and mis-splicing). Upregulation of spliceosome effectors was demonstrated in ko zebrafish.

Similarly, mRNA expression and splicing defects were demonstrated in LCLs from affected individuals. FAM50A pulldown followed by mass spectrometry in transfected HEK293T cells demonstrated enrichment of binding proteins involved in RNA processing and co-immunoprecipitation assays (transfected U-87 cells) suggested that FAM50A interacts with spliceosome U5 and C-complex proteins.

Overall aberrant spliceosome C-complex function is suggested as the underlying pathogenetic mechanism.

Several other neurodevelopmental syndromes are caused by variants in genes encoding C-complex affiliated proteins (incl. EFTUD2, EIF4A3, THOC2, etc.).

Please consider inclusion in the ID panel with green rating and epilepsy panel with amber (seizures in individuals from 2 families).
Sources: Literature
Intellectual disability syndromic and non-syndromic v0.2174 PSAT1 Zornitza Stark Phenotypes for gene: PSAT1 were changed from to Phosphoserine aminotransferase deficiency, MIM# 610992; Neu-Laxova syndrome 2, MIM# 616038
Intellectual disability syndromic and non-syndromic v0.2170 PSAT1 Zornitza Stark reviewed gene: PSAT1: Rating: AMBER; Mode of pathogenicity: None; Publications: 26960553, 17436247, 25152457; Phenotypes: Phosphoserine aminotransferase deficiency, MIM# 610992, Neu-Laxova syndrome 2, MIM# 616038; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability syndromic and non-syndromic v0.1984 NSF Zornitza Stark Marked gene: NSF as ready
Intellectual disability syndromic and non-syndromic v0.1984 NSF Zornitza Stark Gene: nsf has been classified as Amber List (Moderate Evidence).
Intellectual disability syndromic and non-syndromic v0.1984 NSF Zornitza Stark Classified gene: NSF as Amber List (moderate evidence)
Intellectual disability syndromic and non-syndromic v0.1984 NSF Zornitza Stark Gene: nsf has been classified as Amber List (Moderate Evidence).
Intellectual disability syndromic and non-syndromic v0.1983 NSF Zornitza Stark gene: NSF was added
gene: NSF was added to Intellectual disability syndromic and non-syndromic. Sources: Literature
Mode of inheritance for gene: NSF was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: NSF were set to 31675180
Phenotypes for gene: NSF were set to Seizures; EEG with burst suppression; Global developmental delay; Intellectual disability
Review for gene: NSF was set to AMBER
Added comment: Two individuals reported with de novo missense variants in this gene.
Sources: Literature
Intellectual disability syndromic and non-syndromic v0.1981 KAT8 Zornitza Stark gene: KAT8 was added
gene: KAT8 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature
Mode of inheritance for gene: KAT8 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: KAT8 were set to 31794431
Phenotypes for gene: KAT8 were set to Intellectual disability; seizures; autism; dysmorphic features
Review for gene: KAT8 was set to GREEN
Added comment: Eight unrelated individuals reported with de novo variants in this gene and a mouse model. All variants missense, in the chromobarrel domain or the acetyltransferase domain; three individuals had the same variant p.Tyr90Cys . One more individual reported with bi-allelic variants: one missense and one frameshift; carrier parents were normal suggesting that may be haploinsuffiency is not the mechanism.
Sources: Literature
Intellectual disability syndromic and non-syndromic v0.1275 ZMIZ1 Chirag Patel gene: ZMIZ1 was added
gene: ZMIZ1 was added to Intellectual disability, syndromic and non-syndromic_GHQ_VCGS. Sources: Literature
Mode of inheritance for gene: ZMIZ1 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: ZMIZ1 were set to PubMed: 30639322
Phenotypes for gene: ZMIZ1 were set to Neurodevelopmental disorder with dysmorphic facies and distal skeletal anomalies; OMIM #618659
Review for gene: ZMIZ1 was set to GREEN
Added comment: 28 families with spectrum of neurodevelopmental features (including ID, ASD, and ADHD) due to de novo ZNF292 variants (1 family inherited). No functional evidence of specific variants, but ZNF292 is highly expressed in the developing human brain.


14 unrelated patients with neurodevelopmental disorder with dysmorphic facies and distal skeletal anomalies, and de novo heterozygous mutations in the ZMIZ1 gene. Transfection of 3 variants (T300M, c.3112dupA, and K91R) into HEK293T cells resulted in decreased induction of luciferase activity compared to wildtype (although the change for K91R was not statistically significant), suggesting impaired coactivation activity of the mutant proteins. Electroporation of these 3 mutants into progenitor cells in the ventricular zone of embryonic mice cortices resulted in defective neuronal migration to the cortex, as well as morphologic abnormalities of the neurons manifest as rounded cells with aberrantly oriented processes. These findings suggested that the ZMIZ1 mutations disrupted proper neuronal polarization and neuronal migration in the developing cortex. Functional studies of the other variants and additional studies of patient cells were not performed.
Sources: Literature
Intellectual disability syndromic and non-syndromic v0.594 LIPT1 Zornitza Stark Phenotypes for gene: LIPT1 were changed from to Lipoyltransferase 1 deficiency, MIM#616299
Intellectual disability syndromic and non-syndromic v0.591 LIPT1 Zornitza Stark reviewed gene: LIPT1: Rating: GREEN; Mode of pathogenicity: None; Publications: 24341803, 24256811, 29681092; Phenotypes: Lipoyltransferase 1 deficiency, MIM#616299; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal