7-97869140-G-T
Variant summary
Our verdict is Pathogenic. The variant received 13 ACMG points: 13P and 0B. PM2PP2PP3_ModeratePP5_Very_Strong
The NM_001673.5(ASNS):c.17C>A(p.Ala6Glu) variant causes a missense change. The variant allele was found at a frequency of 0.00000558 in 1,613,910 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 Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A6V) has been classified as Uncertain significance.
Frequency
Consequence
NM_001673.5 missense
Scores
Clinical Significance
Conservation
Publications
- congenital microcephaly - severe encephalopathy - progressive cerebral atrophy syndromeInheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Orphanet, Labcorp Genetics (formerly Invitae), ClinGen
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ACMG classification
Our verdict: Pathogenic. The variant received 13 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.00000657 AC: 1AN: 152128Hom.: 0 Cov.: 32 show subpopulations
GnomAD2 exomes AF: 0.0000119 AC: 3AN: 251240 AF XY: 0.0000147 show subpopulations
GnomAD4 exome AF: 0.00000547 AC: 8AN: 1461782Hom.: 0 Cov.: 31 AF XY: 0.00000550 AC XY: 4AN XY: 727162 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.00000657 AC: 1AN: 152128Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1AN XY: 74322 show subpopulations ⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.
Age Distribution
ClinVar
Submissions by phenotype
not provided Pathogenic:2
This sequence change replaces alanine, which is neutral and non-polar, with glutamic acid, which is acidic and polar, at codon 6 of the ASNS protein (p.Ala6Glu). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This missense change has been observed in individual(s) with asparagine synthetase deficiency (PMID: 24139043). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 91842). 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 ASNS protein function with a positive predictive value of 80%. Experimental studies have shown that this missense change affects ASNS function (PMID: 24139043). For these reasons, this variant has been classified as Pathogenic. -
The A6E variant in the ASNS gene was reported previously in a French Canadian family in the compound heterozygous state with the R550C variant in three siblings with progressive microcephaly, infantile epilepsy, profound developmental delay, axial hypotonia, and an abnormal brain MRI (Ruzzo et al., 2013). The A6E variant was not observed in approximately 6500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. The A6E variant is a non-conservative amino acid substitution, which occurs at a position that is conserved across species, and in silico analysis predicts this variant is probably damaging to the protein structure/function. The A6E variant was reported to impair ASNS gene function by reducing protein expression in HEK and COS cells (Ruzzo et al., 2013). The A6E variant is a strong candidate for a pathogenic variant, however the possibility it may be a rare benign variant cannot be excluded. -
Congenital microcephaly - severe encephalopathy - progressive cerebral atrophy syndrome Pathogenic:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at