Clinical Outcome of Hypertrophic Cardiomyopathy in Probands with the Founder Variant c.913_914del in MYBPC3: A Slovenian Cohort Study.

Hypertrophic cardiomyopathy is often caused by pathogenic MYBPC3 variants. The study of Italian patients with HCM and MYBPC3(NM_000256.3):c.913_914del showed a higher disease penetrance in males and a higher frequency of arrhythmias compared to patients with other likely pathogenic and pathogenic (LP/P) MYBPC3 variants. We investigated the clinical outcomes of Slovenian probands with MYBPC3 LP/P variants, estimated the variant penetrance and compared the results with an Italian study. We identified 31 haplotype-matched individuals with MYBPC3:c.913_914del and 34 individuals with other LP/P MYBPC3 variants. We observed some significant differences in clinical and echocardiographic characteristics and frequency of adverse cardiac events between Slovenian and Italian probands with MYBPC3:c913_914del. We were unable to replicate previous findings for MYBPC3:c.913_914del, highlighting the complexity of genotype-phenotype associations.