rs370624118
Variant summary
Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM5PP2PP3_ModeratePP5
The NM_001182.5(ALDH7A1):c.364C>T(p.Arg122Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000626 in 1,614,028 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 Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R122Q) has been classified as Likely pathogenic.
Frequency
Consequence
NM_001182.5 missense
Scores
Clinical Significance
Conservation
Publications
- pyridoxine-dependent epilepsyInheritance: AR Classification: DEFINITIVE, SUPPORTIVE Submitted by: Illumina, Orphanet, ClinGen
- pyridoxine-dependent epilepsy caused by ALDH7A1 mutantInheritance: AR, AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae), Ambry Genetics
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ACMG classification
Our verdict: Likely_pathogenic. The variant received 6 ACMG points.
Transcripts
RefSeq
| Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | MANE | Protein | UniProt |
|---|---|---|---|---|---|---|---|---|
| ALDH7A1 | NM_001182.5 | c.364C>T | p.Arg122Trp | missense_variant | Exon 4 of 18 | ENST00000409134.8 | NP_001173.2 | |
| ALDH7A1 | NM_001201377.2 | c.280C>T | p.Arg94Trp | missense_variant | Exon 4 of 18 | NP_001188306.1 | ||
| ALDH7A1 | NM_001202404.2 | c.364C>T | p.Arg122Trp | missense_variant | Exon 4 of 16 | NP_001189333.2 |
Ensembl
Frequencies
GnomAD3 genomes AF: 0.0000460 AC: 7AN: 152132Hom.: 0 Cov.: 32 show subpopulations
GnomAD2 exomes AF: 0.0000915 AC: 23AN: 251474 AF XY: 0.0000883 show subpopulations
GnomAD4 exome AF: 0.0000643 AC: 94AN: 1461782Hom.: 0 Cov.: 31 AF XY: 0.0000701 AC XY: 51AN XY: 727198 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.0000460 AC: 7AN: 152246Hom.: 0 Cov.: 32 AF XY: 0.0000806 AC XY: 6AN XY: 74428 show subpopulations
Age Distribution
ClinVar
Submissions by phenotype
Pyridoxine-dependent epilepsy Pathogenic:3
This sequence change replaces arginine, which is basic and polar, with tryptophan, which is neutral and slightly polar, at codon 122 of the ALDH7A1 protein (p.Arg122Trp). This variant is present in population databases (rs370624118, gnomAD 0.03%). This missense change has been observed in individual(s) with pyridoxine-dependent epilepsy (internal data). 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: 204863). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is expected to disrupt ALDH7A1 protein function with a positive predictive value of 95%. For these reasons, this variant has been classified as Pathogenic. -
Variant summary: ALDH7A1 c.364C>T (p.Arg122Trp) results in a non-conservative amino acid change located in the Aldehyde dehydrogenase domain (IPR015590) of 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 9.1e-05 in 251474 control chromosomes. This frequency is not significantly higher than estimated for a pathogenic variant in ALDH7A1 causing Pyridoxine-Dependent Epilepsy (9.1e-05 vs 0.0018), allowing no conclusion about variant significance. c.364C>T has been reported in the literature in individuals affected with Pyridoxine-Dependent Epilepsy, and was shown to segregate with disease in two affected brothers (example, Coughlin_2019, Jiao_2020, Jiao_2021, McKnight_2021). These data indicate that the variant is likely to be associated with disease. Experimental evidence evaluating an impact on protein function demonstrated the enzyme activity of the variant to be 81% of wild type (Coughlin_2019). The following publications have been ascertained in the context of this evaluation (PMID: 25969726, 30043187, 31737911, 33868381, 34926809). Four submitters have cited clinical-significance assessments for this variant to ClinVar after 2014 (Pathogenic, n=1, VUS, n=3). Based on the evidence outlined above, the variant was classified as likely pathogenic. -
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Inborn genetic diseases Pathogenic:1
The p.R122W variant (also known as c.364C>T), located in coding exon 4 of the ALDH7A1 gene, results from a C to T substitution at nucleotide position 364. The arginine at codon 122 is replaced by tryptophan, an amino acid with dissimilar properties. This amino acid position is highly conserved in available vertebrate species. The in silico prediction for this alteration is inconclusive. Based on data from gnomAD, the T allele has an overall frequency of 0.009% (26/282864) total alleles studied. The highest observed frequency was 0.031% (11/35440) of Latino alleles. This variant has been identified in conjunction with other ALDH7A1 variants in individuals with features consistent with autosomal recessive pyridoxine-dependent epilepsy; in at least one instance, the variants were identified in trans (Coughlin, 2019; Jiao, 2021). -
not provided Pathogenic:1
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: 30043187, 32956737, 33868381, 31737911, 34926809) -
not specified Uncertain:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at