ClinVar Genomic variation as it relates to human health

The p.Cys271Tyr variant in MC4R has been reported in at least 7 individuals with obesity, segregated with disease in these 7 affected relatives from 1 family (PMID: 12646665), and was absent from large population studies. This variant has also been reported in ClinVar as pathogenic (Variation ID: 14329). In vitro functional studies provide some evidence that the p.Cys271Tyr variant may impact protein function (PMID: 12646665, 12588803). However, these types of assays may not accurately represent biological function. Computational prediction tools and conservation analyses suggest that this variant may impact the protein, though this information is not predictive enough to determine pathogenicity. One additional likely pathogenic variant, resulting in a different amino acid change at the same position, p.Cys271Arg, has been reported in association with disease in the literature and in ClinVar, slightly supporting that a change at this position may not be tolerated (PMID: 14504270, 18559663, 12646665/Variation ID: 372803). In summary, this variant meets criteria to be classified as pathogenic for obesity in an autosomal dominant manner based on the functional evidence resulting in absence of normal MC4R function and the demonstration of the variant cosegregating with disease in a large family. ACMG/AMP Criteria applied: PS3, PP1_strong, PM2, PP3, PM5_supporting (Richards 2015).

proposed classification - variant undergoing re-assessment, contact laboratory

The MC4R c.812G>A variant is predicted to result in the amino acid substitution p.Cys271Tyr. This variant has been reported in the heterozygous state to be causative for autosomal dominant MC4R-related obesity (Yeo et al. 2003. PubMed ID: 12588803; Farooqi et al. 2003. PubMed ID: 12646665). This variant has not been reported in a large population database, indicating this variant is rare. This variant is interpreted as pathogenic.