Uncertain significance, criteria provided, single submitter | clinical testing | GeneDx | Dec 23, 2021 | Reported as a variant of uncertain significance in association with cardiomyopathy (Whiffin et al., 2017; Kolokotronis et al., 2020); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Reported in ClinVar (ClinVar Variant ID# 180968; Landrum et al., 2016); This variant is associated with the following publications: (PMID: 31980526, 26582918, 28518168, 32659924) - |
Uncertain significance, no assertion criteria provided | provider interpretation | Stanford Center for Inherited Cardiovascular Disease, Stanford University | Nov 01, 2017 | p.Pro794Leu (c.2381C>T) in exon 24 of the MYBPC3 gene (NM_000256.3; chr11-47359273-G-A) SCICD Classification: variant of uncertain significance, likely benign based on relatively high frequency in the general population, lack of case data and lack of segregation data. We do not feel it is suitable for assessing risk in healthy relatives ("predictive genetic testing"). Gene-level evidence: MYBPC3: Pathogenic variants in MYBPC3 are one of the most common causes of hypertrophic cardiomyopathy (HCM). Splicing and other protein-truncating variants in MYBPC3 are a frequent cause of HCM (Erdmann et al. 2001 & 2003; Stenson et al 2003; Harvard Sarcomere Protein Gene Mutation Database). However, there are several missense variants in MYBPC3 known to cause disease. MYBPC3 encodes cardiac myosin-binding protein C. It binds myosin heavy chain and titin. Phosphorylation of MYBPC3 modulates contraction of the sarcomere. Region level data: Amr et al 2016: patients with HCM with variants in this region are overrepresented compared to controls. Case data (not including our patient): at least 3 · ClinVar: § GeneDx (likely path), Laboratory for Molecular Medicine (VUS) and Blueprint Genetics (VUS): § LMM saw this variant in a whole exome/genome case but was not fully reviewed. § GeneDx saw this variant in one patient with HCM who had another pathogenic variant. However, neither of these variants have been reviewed since updated variant classification guidelines were published § Blueprint has downgraded their classification of this variant to VUS from likely path. · Cases in the literature: none reported Segregation data: none reported Functional data: none reported In silico data (missense variants only): Per the test report, "Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain." Conservation data: The proline at codon 794 is not completely conserved across species. Nearby pathogenic variants at this codon or neighboring codons: A truncating variant at this codon, p.Pro794fs*26, is reported in 1 of ~400 patients with HCM (Van Driest et al 2004). Other truncating variants are nearby (p.Gln791Ter, p.Trp792Valfs, p.Trp792Ter, p.Pro795Leufs, p.Gly799Trpfs). A missense variant at a nearby codon is classified as pathogenic by multiple labs: p.Trp792Arg. Population data: Highest MAF in the South Asian population: 0.079%. The variant was reported online in 27 of 99,709 individuals in the Genome Aggregation Consortium Dataset (gnomAD; http://gnomad.broadinstitute.org/), which currently includes variant calls on >140,000 unrelated individuals of African, Asian, European, Ashkenazi, Latino descent. Specifically, the variant was observed in 19 of 12,073 individuals of South Asian descent (MAF=0.079%), 1 of 2,571 individuals of "other" descent, 6 of 41,715 individuals of European descent and 1 of 13,128 individuals of Latino descent. The phenotype of those individuals is not publicly available. The dataset is comprised of multiple cohorts, some of which were recruited from the general population, others were enriched for common cardiovascular disease. - |