chr1-29202004-C-T
Variant summary
Our verdict is Pathogenic. The variant received 14 ACMG points: 14P and 0B. PM2PP3_StrongPP5_Very_Strong
The NM_016011.5(MECR):c.695G>A(p.Gly232Glu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000242 in 1,614,044 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 (★★).
Frequency
Consequence
NM_016011.5 missense
Scores
Clinical Significance
Conservation
Publications
- dystonia, childhood-onset, with optic atrophy and basal ganglia abnormalitiesInheritance: AR Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
- Leigh syndromeInheritance: AR Classification: MODERATE Submitted by: ClinGen
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ACMG classification
Our verdict: Pathogenic. The variant received 14 ACMG points.
Transcripts
RefSeq
| Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | MANE | Protein | UniProt |
|---|---|---|---|---|---|---|---|---|
| MECR | NM_016011.5 | c.695G>A | p.Gly232Glu | missense_variant | Exon 6 of 10 | ENST00000263702.11 | NP_057095.4 |
Ensembl
Frequencies
GnomAD3 genomes AF: 0.0000197 AC: 3AN: 152162Hom.: 0 Cov.: 32 show subpopulations
GnomAD2 exomes AF: 0.0000716 AC: 18AN: 251486 AF XY: 0.000103 show subpopulations
GnomAD4 exome AF: 0.0000246 AC: 36AN: 1461882Hom.: 0 Cov.: 31 AF XY: 0.0000303 AC XY: 22AN XY: 727244 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.0000197 AC: 3AN: 152162Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1AN XY: 74312 show subpopulations
Age Distribution
ClinVar
Submissions by phenotype
not provided Pathogenic:3
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This sequence change replaces glycine, which is neutral and non-polar, with glutamic acid, which is acidic and polar, at codon 232 of the MECR protein (p.Gly232Glu). This variant is present in population databases (rs762913101, gnomAD 0.2%). This missense change has been observed in individual(s) with childhood-onset dystonia with optic atrophy and basal ganglia abnormalities (PMID: 27817865). 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: 374878). 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 MECR protein function with a positive predictive value of 80%. For these reasons, this variant has been classified as Pathogenic. -
Published functional studies suggest a damaging effect as yeast transfected with G232E showed absence of protein lipoylation and protein expression (Heimer et al., 2016); 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: 27817865, 32445240) -
Dystonia, childhood-onset, with optic atrophy and basal ganglia abnormalities Pathogenic:2
Variant summary: MECR c.695G>A (p.Gly232Glu) results in a non-conservative amino acid change located in the Alcohol dehydrogenase-like, C-terminal domain (IPR013149) 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 7.2e-05 in 251486 control chromosomes. This frequency is not significantly higher than estimated for a pathogenic variant in MECR causing Dystonia, Childhood-Onset, With Optic Atrophy And Basal Ganglia Abnormalities, allowing no conclusion about variant significance. c.695G>A has been reported in the literature in multiple compound heterozygous individuals affected with Dystonia, Childhood-Onset, With Optic Atrophy And Basal Ganglia Abnormalities (e.g. Heimer_2016, Alves_2018, Baide-Mairena_2022, Gupta_2023). These data indicate that the variant is very likely to be associated with disease. At least one publication reports experimental evidence evaluating an impact on protein function. The most pronounced variant effect results in impaired ability to rescue a lactate-dependent growth phenotype in a yeast complementation study and impaired lipoylation (Heimer_2016). The following publications have been ascertained in the context of this evaluation (PMID: 32445240, 34988976, 36262091, 27817865). ClinVar contains an entry for this variant (Variation ID: 374878). Based on the evidence outlined above, the variant was classified as pathogenic. -
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MECR-related disorder Pathogenic:1
The MECR c.695G>A variant is predicted to result in the amino acid substitution p.Gly232Glu. This variant has been reported in the compound heterozygous state in multiple unrelated affected individuals, and functional studies support its pathogenicity (Heimer et al. 2016. PubMed ID: 27817865; Alves et al. 2020. PubMed ID: 32445240, supplementary data; Martin-Saavedra et al. 2021. PubMed ID: 34052969). Pathogenic variants in MECR have been associated with autosomal recessive childhood-onset dystonia, with optic atrophy and basal ganglia abnormalities (OMIM #617282). This variant is reported in 0.16% of alleles in individuals of Ashkenazi Jewish descent in gnomAD (http://gnomad.broadinstitute.org/variant/1-29528516-C-T). This variant is interpreted as likely pathogenic. -
Mitochondrial disease Pathogenic:1
The MECR c.695G>A (p.Gly232Glu) missense variant results in the substitution of glycine at amino acid position 232 with glutamine. This variant has been reported in a compound heterozygous state with the c.830+2dup variant in four individuals with features of primary mitochondrial disease from three families, at least two of whom had Jewish ancestry (PMID: 27817865; PMID: 32445240; PMID: 34052969). Fibroblasts from compound heterozygous individuals showed reduced MECR protein expression and reduced protein lipoylation. Reduced electron transport capacity was also observed in some cases (PMID: 27817865). The c.695G>A variant has also been reported in trans with a stop-gained variant in an additional affected individual (PMID: 27817865). The highest frequency of this allele in the Genome Aggregation Database is 0.001587 in the Ashkenazi Jewish population (version 2.1.1). This frequency is consistent with the increased prevalence of MECR-related primary mitochondrial disease among individuals with Ashkenazi Jewish ancestry (PMID: 31070877). Yeast complementation studies of this variant, which is located within the cofactor binding domain, demonstrated an impaired ability to rescue the lactate-dependent growth phenotype compared to wildtype. The c.695G>A variant also showed reduced protein expression/stability and impaired lipoylation when expressed in yeast (PMID: 27817865). This variant was identified in a compound heterozygous state with the c.830+2dup variant and segregated with disease. Based on the available evidence, the c.695G>A (p.Gly232Glu) variant is classified as likely pathogenic for primary mitochondrial disease. -
Optic atrophy;C0752202:Childhood Onset Dystonias Pathogenic:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at