rs138279074
Variant summary
Our verdict is Uncertain significance. Variant got 1 ACMG points: 2P and 1B. PM2BP4
The NM_054012.4(ASS1):c.299G>A(p.Arg100His) variant causes a missense change. The variant allele was found at a frequency of 0.000158 in 1,613,208 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).
Frequency
Consequence
NM_054012.4 missense
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Uncertain_significance. Variant got 1 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.000184 AC: 28AN: 152192Hom.: 0 Cov.: 33
GnomAD3 exomes AF: 0.000180 AC: 45AN: 250286Hom.: 0 AF XY: 0.000185 AC XY: 25AN XY: 135496
GnomAD4 exome AF: 0.000155 AC: 227AN: 1460900Hom.: 0 Cov.: 32 AF XY: 0.000162 AC XY: 118AN XY: 726744
GnomAD4 genome AF: 0.000184 AC: 28AN: 152308Hom.: 0 Cov.: 33 AF XY: 0.000215 AC XY: 16AN XY: 74472
ClinVar
Submissions by phenotype
Citrullinemia type I Uncertain:4
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This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). Publications were found based on this search. However, the evidence from the literature, in combination with allele frequency data from public databases where available, was not sufficient to rule this variant in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -
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not provided Uncertain:2
The p.Arg100His variant (rs138279074) has not been reported in the medical literature, nor is it listed in gene-specific variant databases. It is listed in the Genome Aggregation Database (gnomAD) browser with an overall frequency of 0.017% (identified in 46 out of 276,470 chromosomes). The arginine at codon 100 is moderately conserved considering 12 species (Alamut software v2.8.1), and computational analyses suggest this variant does not have a significant effect on ASS1 protein structure/function (SIFT: tolerated and PolyPhen2: benign). However, based on the available information, the clinical significance of the p.Arg100His variant cannot be determined with certainty. -
Reported in an individual with cholestasis, failure to thrive, and mildly elevated citrulline who was also heterozygous for another variant in ASS1 (Diez-Fernandez et al., 2017); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 30285816, 34426522, 31469252, 28111830) -
not specified Uncertain:1
Variant summary: ASS1 c.299G>A (p.Arg100His) results in a non-conservative amino acid change located in the Arginosuccinate synthase-like, N-terminal domain (IPR048267) of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 0.00018 in 250286 control chromosomes (gnomAD). This frequency is not significantly higher than estimated for a pathogenic variant in ASS1 causing Citrullinemia Type I (0.00018 vs 0.0041), allowing no conclusion about variant significance. c.299G>A has been reported in the literature in individuals affected with Citrullinemia Type I (Diez-Fernandez_2017, Bijarnia-Mahay_2018, Zielonka_2019, Shum_2023). These data indicate that the variant may be associated with disease. At least one publication reports experimental evidence evaluating an impact on protein function using a biallelic expression system where the variant was expressed together with a pathogenic variant (Zielonka_2019), however, this does not allow convincing conclusions about the variant effect in isolation. The following publications have been ascertained in the context of this evaluation (PMID: 28111830, 30285816, 31469252, 37443404). ClinVar contains an entry for this variant (Variation ID: 439417). Based on the evidence outlined above, the variant was classified as VUS-possibly pathogenic. -
Inborn genetic diseases Uncertain:1
(Bijarnia-Mahay, 2018) Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -
Citrullinemia Uncertain:1
This sequence change replaces arginine, which is basic and polar, with histidine, which is basic and polar, at codon 100 of the ASS1 protein (p.Arg100His). This variant is present in population databases (rs138279074, gnomAD 0.04%). This missense change has been observed in individual(s) with citrullinemia type 1 (PMID: 28111830, 30285816, 31469252). ClinVar contains an entry for this variant (Variation ID: 439417). 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 not expected to disrupt ASS1 protein function. This variant disrupts the p.Arg100 amino acid residue in ASS1. Other variant(s) that disrupt this residue have been observed in individuals with ASS1-related conditions (PMID: 28111830), which suggests that this may be a clinically significant amino acid residue. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at