Abstract 4138690: A Case of Hypertrophic Cardimyopathy: Digenic Variants of Uncertain Significance Mutations in MHY7 and RYR2 Genes

Abstract

Introduction: Hypertrophic Cardiomyopathy (HCM) is primarily a disease caused by mutations in single genes, but around 5% of HCM patients, exhibit 2 (digenic) or more (oligogenic) causal mutations in the same gene or in different genes. We present a case of familial HCM with variants of uncertain significance (VUS) mutations in the MYH7 and RYR2 genes, highlighting the complexity of genetic inheritance and its implications on disease severity. Case presentation: A 40-year-old male presented with a history of hypertension, HCM, and two prior myocardial infarctions. He had syncope, non-sustained ventricular tachycardia, and a family history of sudden cardiac death (SCD) in his maternal grandfather. A dual-chamber ICD was placed for primary prevention of SCD because of his high-risk profile. Echocardiography demonstrated normal LV size and function with moderate asymmetric septal hypertrophy. Cardiac MRI indicated diffuse asymmetric hypertrophy and a 10.9% LV myocardial scar burden. Left heart catheterization revealed normal coronary arteries with LVOT gradient up to 60 mmHg, consistent with HCM. Genetic testing revealed VUS in the MYH7 (c.1305G>A, p.Met435Ile) and RYR2 (c.10528C>A, p.Arg3510Ser) genes (Figure 1). Further family genetic testing confirmed these VUS mutations in multiple relatives (Figure 2). Discussion: The identification of VUS mutations in MYH7 and RYR2 genes in multiple family members highlights the complexity of genetic inheritance in HCM. These findings underscore the challenges in clinical interpretation and risk stratification, as the co-occurrence of mutations in different genes may have synergistic effects on disease severity and phenotype expression. Comprehensive genetic evaluation, including family studies, is crucial for understanding the clinical significance of these mutations and guiding personalized management strategies. Further research is needed to elucidate the impact of VUS mutations on the clinical outcomes of HCM patients.