6-49457872-G-T
Variant summary
Our verdict is Pathogenic. The variant received 19 ACMG points: 19P and 0B. PM1PM2PM5PP2PP3_StrongPP5_Very_Strong
The NM_000255.4(MMUT):c.572C>A(p.Ala191Glu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000421 in 1,613,302 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. A191T) has been classified as Likely pathogenic.
Frequency
Consequence
NM_000255.4 missense
Scores
Clinical Significance
Conservation
Publications
- methylmalonic aciduria due to methylmalonyl-CoA mutase deficiencyInheritance: AR Classification: DEFINITIVE, STRONG Submitted by: ClinGen, Labcorp Genetics (formerly Invitae), G2P
- vitamin B12-unresponsive methylmalonic acidemia type mut-Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- vitamin B12-unresponsive methylmalonic acidemia type mut0Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
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ACMG classification
Our verdict: Pathogenic. The variant received 19 ACMG points.
Transcripts
RefSeq
| Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | MANE | Protein | UniProt |
|---|---|---|---|---|---|---|---|---|
| MMUT | NM_000255.4 | c.572C>A | p.Ala191Glu | missense_variant | Exon 3 of 13 | ENST00000274813.4 | NP_000246.2 | |
| MMUT | XM_005249143.4 | c.572C>A | p.Ala191Glu | missense_variant | Exon 3 of 13 | XP_005249200.1 |
Ensembl
Frequencies
GnomAD3 genomes AF: 0.0000395 AC: 6AN: 152076Hom.: 0 Cov.: 32 show subpopulations
GnomAD2 exomes AF: 0.0000318 AC: 8AN: 251216 AF XY: 0.0000221 show subpopulations
GnomAD4 exome AF: 0.0000424 AC: 62AN: 1461226Hom.: 0 Cov.: 32 AF XY: 0.0000426 AC XY: 31AN XY: 727006 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.0000395 AC: 6AN: 152076Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1AN XY: 74270 show subpopulations
Age Distribution
ClinVar
Submissions by phenotype
Methylmalonic aciduria due to methylmalonyl-CoA mutase deficiency Pathogenic:4Other:1
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This submission and the accompanying classification are no longer maintained by the submitter.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. -
The variant is observed at an extremely low frequency in the gnomAD v2.1.1 dataset (total allele frequency: 0.003%). In silico tool predictions suggest damaging effect of the variant on gene or gene product (REVEL: 0.96; 3Cnet: 0.83). Same nucleotide change resulting in same amino acid change has been previously reported as pathogenic/likely pathogenic with strong evidence (ClinVar ID: VCV000203854). The variant has been reported to be in trans with a pathogenic variant as either compound heterozygous or homozygous in at least 4 similarly affected unrelated individuals (PMID: 16281286). A different missense change at the same codon (p.Ala191Thr) has been reported to be associated with MMUT-related disorder (ClinVar ID: VCV000451101). Therefore, this variant is classified as Pathogenic according to the recommendation of ACMG/AMP guideline. -
not provided Pathogenic:3
Not observed at a significant frequency in large population cohorts (gnomAD); Published functional studies demonstrate that this variant disrupts protein polarity (Forny et al., 2014); 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: 15643616, 31260114, 31525265, 30577886, 26790480, 16281286, 17113806, 2595903, 24059531, 32754920, 9554742, 15781192, 17957493, 25125334) -
The p.Ala191Glu (rs760782399) is one a commonly associated variants with Methylmalonic aciduria (Adjalla 1998, Worgan 2006, and GeneReviews pubmed ID 20301409). This variant is listed in the Genome Aggregation Database (gnomAD) with an overall population frequency of 0.004 percent (identified on 10 out of 277,004 chromosomes) and has been reported to the ClinVar database with a pathogenic classification (variation ID: 203854). Expression of the variant MUT protein in bacteria results in poor solubility (Forny 2014) consistent with high conservation of the alanine at position 191 and damaging effects by computational predictor algorithms (SIFT: damaging, PolyPhen-2: probably damaging). Based on these observations the p.Ala191Glu variant is considered to be likely pathogenic. -
This sequence change replaces alanine, which is neutral and non-polar, with glutamic acid, which is acidic and polar, at codon 191 of the MUT protein (p.Ala191Glu). This variant is present in population databases (rs760782399, gnomAD 0.008%). This missense change has been observed in individuals with methylmalonic acidemia (PMID: 15643616, 16281286, 17113806, 17957493, 20549364, 24059531). ClinVar contains an entry for this variant (Variation ID: 203854). 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 MUT protein function with a positive predictive value of 95%. Experimental studies have shown that this missense change affects MUT function (PMID: 16281286, 17113806). For these reasons, this variant has been classified as Pathogenic. -
Methylmalonic aciduria due to complete methylmalonyl-CoA mutase deficiency Pathogenic:1
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Abnormality of metabolism/homeostasis Pathogenic:1
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Methylmalonic acidemia Pathogenic:1
Variant summary: The MUT c.572C>A (p.Ala191Glu) variant located in the alpha chain, catalytic domain (via InterPro) involves the alteration of a conserved nucleotide and is predicted to be damaging by 4/4 in silico tools (SNPs&GO not captured due to low reliability index). This variant was found in 6/121172 control chromosomes from ExAC at a heterozygous allele frequency of 0.0000495, which does not exceed the estimated maximal expected allele frequency of a pathogenic MUT variant (0.0024152). This variant is a frequent disease-causing mutation found in several patients in homozygous as well as compound heterozygous state with other likely pathogenic/pathogenic variants with consistent biochemical phenotype (Adjalla_1998, Worgan_2006, de Keyzer_2009, Nizon_2013, Manoli_2016). In addition, one in vitro functional study showed that this variant leads to impairment of folding as well catalytic activity of protein (Forny_2014). Multiple clinical diagnostic laboratories/reputable databases have classified this variant as pathogenic. Taken together, this variant is classified as Pathogenic. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at