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Intellectual disability syndromic and non-syndromic v1.277 TTC1 Zornitza Stark Marked gene: TTC1 as ready
Intellectual disability syndromic and non-syndromic v1.277 TTC1 Zornitza Stark Gene: ttc1 has been classified as Red List (Low Evidence).
Intellectual disability syndromic and non-syndromic v1.276 TTC1 Zornitza Stark gene: TTC1 was added
gene: TTC1 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature
Mode of inheritance for gene: TTC1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TTC1 were set to 40879651
Phenotypes for gene: TTC1 were set to Pontocerebellar hypoplasia, MONDO:0020135, TTC1-related
Review for gene: TTC1 was set to RED
Added comment: Four individuals from two families reported with the same homozygous missense variant, NM_003314.3: c.784 T > G, p.Phe262Val. No other supporting data.
Sources: Literature
Intellectual disability syndromic and non-syndromic v0.6158 TTC19 Zornitza Stark Marked gene: TTC19 as ready
Intellectual disability syndromic and non-syndromic v0.6158 TTC19 Zornitza Stark Gene: ttc19 has been classified as Green List (High Evidence).
Intellectual disability syndromic and non-syndromic v0.6158 TTC19 Zornitza Stark Phenotypes for gene: TTC19 were changed from to Mitochondrial complex III deficiency, nuclear type 2, MIM#615157
Intellectual disability syndromic and non-syndromic v0.6157 TTC19 Zornitza Stark Publications for gene: TTC19 were set to
Intellectual disability syndromic and non-syndromic v0.6156 TTC19 Zornitza Stark Mode of inheritance for gene: TTC19 was changed from Unknown to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability syndromic and non-syndromic v0.6155 TTC19 Zornitza Stark reviewed gene: TTC19: Rating: GREEN; Mode of pathogenicity: None; Publications: 21278747, 23532514, 24368687, 24397319; Phenotypes: Mitochondrial complex III deficiency, nuclear type 2, MIM#615157; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability syndromic and non-syndromic v0.2659 TTC5 Konstantinos Varvagiannis gene: TTC5 was added
gene: TTC5 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature
Mode of inheritance for gene: TTC5 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TTC5 were set to 29302074; 32439809
Phenotypes for gene: TTC5 were set to Central hypotonia; Global developmental delay; Intellectual disability; Abnormality of nervous system morphology; Microcephaly; Abnormality of the face; Behavioral abnormality; Abnormality of the genitourinary system
Penetrance for gene: TTC5 were set to Complete
Review for gene: TTC5 was set to GREEN
Added comment: Hu et al (2019 - PMID: 29302074) reported briefly on 3 individuals from 2 consanguineous families (from Turkey and Iran) with biallelic TTC5 variants. Features included DD (3/3), ID (severe in 2/2 with relevant age), microcephaly (3/3), brain abnormalities, etc. A nonsense and a variant affecting splice site were identified by WES/WGS.

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In a recent report, Rasheed et al (2020 - PMID: 32439809) report on the phenotype of 8 individuals - belonging to 5 consanguineous families - all 8 harboring homozygous TTC5 mutations.

Frequent features included hypotonia (6/8), motor and speech delay, moderate to severe ID (10/10 of relevant age - inclusion of less severely affected subjects was not considered by study design), brain MRI abnormalities (8/8). Other findings included microcephaly in some (6/11), behavioral abnormalities in few (autistic behavior in 2/8, aggression in 2/8), genitourinary anomalies (2/8), seizures (1/11). Facial phenotype incl. thin V-shaped upper lip, low-set ears (in most) and/or additional features.

TTC5 encodes a 440 aa protein, functioning as a scaffold to stabilise p300-JMY interactions. Apart from this role in nucleus, it has functions in the cytoplasm (inhibiting actin nucleataion, autophagosome formation, etc).

The gene has ubiquitous expression, highest in brain.

All variants were identified following WES - as the best candidates - in affected individuals with compatible Sanger studies in all affected family members and carrier parents.

2 missense and 2 nonsense variants were identified with the 2 missense SNVs localizing within TPR domains. qRT-PCR studies for a nonsense variant localizing 19 nt before the last exon, revealed fourfold decreased expression in affected individuals compared to carriers.

Families from Egypt shared a homozygous ~6.3 Mb haplotype block spanning TTC5, suggesting that p.(Arg263Ter) is likely a founder mutation.

The authors underscore some phenotypic (though not facial) similarities with Rubinstein-Taybi syndrome 2 due to EP300 mutations (in line with the role of TTC5).

Biallelic variants in genes encoding other members of the TTC family (containing a TPR motif), e.g. TTC8 or TTC15 cause disorders with neurologic manifestations (and DD/ID).
Sources: Literature
Intellectual disability syndromic and non-syndromic v0.0 TTC19 Zornitza Stark gene: TTC19 was added
gene: TTC19 was added to Intellectual disability, syndromic and non-syndromic_GHQ. Sources: Expert Review Green,Genetic Health Queensland
Mode of inheritance for gene: TTC19 was set to Unknown