rs770944877
Variant summary
Our verdict is Pathogenic. The variant received 19 ACMG points: 19P and 0B. PM1PM2PM5PP2PP3_StrongPP5_Very_Strong
The NM_054012.4(ASS1):c.349G>A(p.Gly117Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000267 in 1,612,654 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G117D) has been classified as Likely pathogenic.
Frequency
Consequence
NM_054012.4 missense
Scores
Clinical Significance
Conservation
Publications
- citrullinemia type IInheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), ClinGen, Myriad Women’s Health, G2P
- acute neonatal citrullinemia type IInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- adult-onset citrullinemia type IInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
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ACMG classification
Our verdict: Pathogenic. The variant received 19 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.00000657 AC: 1AN: 152226Hom.: 0 Cov.: 33 show subpopulations
GnomAD2 exomes AF: 0.0000121 AC: 3AN: 247280 AF XY: 0.0000223 show subpopulations
GnomAD4 exome AF: 0.0000288 AC: 42AN: 1460428Hom.: 0 Cov.: 32 AF XY: 0.0000275 AC XY: 20AN XY: 726450 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.00000657 AC: 1AN: 152226Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0AN XY: 74358 show subpopulations
Age Distribution
ClinVar
Submissions by phenotype
Citrullinemia type I Pathogenic:6
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This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -
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Citrullinemia Pathogenic:2
This sequence change replaces glycine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 117 of the ASS1 protein (p.Gly117Ser). This variant is present in population databases (rs770944877, gnomAD 0.003%). This missense change has been observed in individual(s) with citrullinemia type I (PMID: 12815590, 16124451, 27287393). ClinVar contains an entry for this variant (Variation ID: 556029). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt ASS1 protein function with a positive predictive value of 80%. Experimental studies have shown that this missense change affects ASS1 function (PMID: 27287393). For these reasons, this variant has been classified as Pathogenic. -
Variant summary: ASS1 c.349G>A (p.Gly117Ser) results in a non-conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 1.2e-05 in 247280 control chromosomes. c.349G>A has been reported in the literature in multiple individuals affected with Citrullinemia Type I, including in homozygotes with neonatal/infantile onset (e.g. Diez-Fernandez_2016). These data indicate that the variant is very likely to be associated with disease. At least one publication reports experimental evidence evaluating an impact on protein function. The most pronounced variant effect results in a complete loss of normal argininosuccinate synthetase enzyme activity (e.g. Diez-Fernandez_2016). The following publication has been ascertained in the context of this evaluation (PMID: 27287393). Five submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as pathogenic (n=4) or likely pathogenic (n=1). Based on the evidence outlined above, the variant was classified as pathogenic. -
ASS1-related disorder Pathogenic:1
The ASS1 c.349G>A variant is predicted to result in the amino acid substitution p.Gly117Ser. This variant has been reported in the homozygous state in several patients with a biochemical diagnosis of citrullinemia (Gao et al. 2003. PubMed ID: 12815590; Wasant et al. 2005. PubMed ID: 16124451; Diez-Fernandez et al. 2016. PubMed ID: 27287393). The p.Gly117Ser change was reported to decrease ASS1 enzyme activity to <2% of wild-type (Diez-Fernandez et al. 2016. PubMed ID: 27287393). This variant is reported in 0.0027% of alleles in individuals of European (Non-Finnish) descent in gnomAD. This variant is interpreted as pathogenic. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at