2-27313031-C-T
Variant summary
Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PM1PM2PM5PP3_StrongPP5_Very_Strong
The NM_002437.5(MPV17):c.149G>A(p.Arg50Gln) variant causes a missense change. The variant allele was found at a frequency of 0.0000109 in 1,461,886 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. R50W) has been classified as Pathogenic.
Frequency
Consequence
NM_002437.5 missense
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Pathogenic. Variant got 18 ACMG points.
Transcripts
RefSeq
Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | MANE | Protein | UniProt |
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MPV17 | NM_002437.5 | c.149G>A | p.Arg50Gln | missense_variant | Exon 3 of 8 | ENST00000380044.6 | NP_002428.1 | |
MPV17 | XM_005264326.5 | c.149G>A | p.Arg50Gln | missense_variant | Exon 3 of 8 | XP_005264383.1 | ||
MPV17 | XM_017004151.2 | c.101G>A | p.Arg34Gln | missense_variant | Exon 3 of 8 | XP_016859640.1 |
Ensembl
Frequencies
GnomAD3 genomes Cov.: 32
GnomAD3 exomes AF: 0.0000119 AC: 3AN: 251478Hom.: 0 AF XY: 0.00 AC XY: 0AN XY: 135912
GnomAD4 exome AF: 0.0000109 AC: 16AN: 1461886Hom.: 0 Cov.: 31 AF XY: 0.0000124 AC XY: 9AN XY: 727242
GnomAD4 genome Cov.: 32
ClinVar
Submissions by phenotype
not provided Pathogenic:3
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The frequency of this variant in the general population is consistent with pathogenicity (http://gnomad.broadinstitute.org). This variant segregates with disease in multiple families. Computational tools predict that this variant is damaging. -
This sequence change replaces arginine, which is basic and polar, with glutamine, which is neutral and polar, at codon 50 of the MPV17 protein (p.Arg50Gln). This variant is present in population databases (rs121909721, gnomAD 0.003%). This missense change has been observed in individuals with mitochondrial DNA depletion syndrome or Navajo neurohepatopathy (PMID: 16582910, 16909392, 28209105). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 16160). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. Experimental studies have shown that this missense change affects MPV17 function (PMID: 16582910, 30833296). For these reasons, this variant has been classified as Pathogenic. -
Mitochondrial DNA depletion syndrome 6 (hepatocerebral type) Pathogenic:2Other:1
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Mitochondrial disease Pathogenic:1
Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Pathogenic. Following criteria are met: 0102 - Loss of function is a known mechanism of disease in this gene and is associated with mitochondrial DNA depletion syndrome 6 (hepatocerebral type) (MIM#256810) and Charcot-Marie-Tooth disease, axonal, type 2EE (MIM#618400). (I) 0106 - This gene is associated with autosomal recessive disease. There is currently no clear genotype-phenotype correlation, however, a trend for longer survival has been reported in individuals with biallelic pathogenic missense variants compared to individuals with biallelic null variants or individuals compound heterozygus for missense and null variants (PMID: 29282788).(I) 115 - Variants in this gene are known to have variable expressivity (PMID: 29282788). (I) 0200 - Variant is predicted to result in a missense amino acid change from arginine to glutamine. (I) 0251 - This variant is heterozygous. (I) 0304 - Variant is present in gnomAD <0.01 for a recessive condition (v2: 4 heterozygotes, 0 homozygotes). (SP) 0309 - An alternative amino acid change at the same position has been observed in gnomAD (v2) (3 heterozygotes, 0 homozygotes). (I) 0501 - Missense variant consistently predicted to be damaging by multiple in silico tools or highly conserved with a major amino acid change. (SP) 0604 - Variant is not located in an established domain, motif, hotspot or informative constraint region. (I) 0801 - This variant has strong previous evidence of pathogenicity in unrelated individuals. This variant has been classified as pathogenic by multiple clinical laboratories in ClinVar and has been reported in homozygous and compound heterozygous individuals with hepatocerebral mitochondrial DNA depletion syndrome, also referred to as Navajo neurohepatopathy (PMIDs: 32703289, 16909392). (SP) 1203 - This variant has been shown to be de novo in the proband (parental status confirmed) (by trio analysis). (SP) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -
Mitochondrial DNA depletion syndrome Pathogenic:1
Variant summary: MPV17 c.149G>A (p.Arg50Gln) results in a conservative amino acid change in 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 1.2e-05 in 251478 control chromosomes (gnomAD). c.149G>A has been reported in the literature in multiple homozygous individuals affected with Mitochondrial DNA Depletion Syndrome (MPV17 Related disorder) and the variant segregated with the disease (examples: Spinazzola_2006 and Karadimas_2006). These data indicate that the variant is very likely to be associated with disease. At least one publication reports experimental evidence suggesting that the R50Q mutation causes protein instability and decay (Karadimas_2006). Four clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 and all classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -
MPV17-related disorder Pathogenic:1
The MPV17 c.149G>A variant is predicted to result in the amino acid substitution p.Arg50Gln. This variant has been previously reported to be pathogenic for the autosomal recessive hepatocerebral form of mitochondrial DNA depletion syndrome (Spinazzola et al. 2006. PubMed ID: 16582910; Shimura et al. 2020. PubMed ID: 32703289). It has been also documented as a founder pathogenic variant for Navajo neurohepatopathy among Navajo children in the southwestern United States (Karadimas et al. 2006. PubMed ID: 16909392). This variant is reported in 0.0031% of alleles in individuals of European (Non-Finnish) descent in gnomAD (http://gnomad.broadinstitute.org). This variant is interpreted as pathogenic. -
Charcot-Marie-Tooth disease, axonal, type 2EE Pathogenic:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at