Early manifestation of MyBPC3-associated hypertrophic cardiomyopathy in childhood: from genotype to phenotype.

Hypertrophic cardiomyopathy (HCM) is the most common hereditary myocardial disease, which occurs with a frequency of 1:500-1:200 of the adult population in all ethnic groups. In the pediatric population, the HCM prevalence is about 1 in 47,000. The disease is characterized by pronounced genetic heterogeneity, however, most cases of HCM are caused by rare variants in the MYH7 and MyBPC3 genes, with more than 90% of mutations in the MyBPC3 gene representing shortening variants leading to the formation of a premature stop codon. In most patients with a single shortening variant in the MyBPC3 gene, clinical manifestations develop over the age of 35, and cases of manifestation in childhood are quite rare. Therefore, the detection of atypically early cases of manifestation always raises questions about the genetic and non-genetic factors influencing the development of the disease. We present a description of a clinical case of MyBPC3-associated HCM in a child characterized by rapid disease progression, development of left ventricular outflow tract obstruction, and the need for cardiac surgery at the age of 12 years. The report presents the results of dynamic follow-up of the patient for eight years before and after surgical treatment. The features of the course of the disease caused by the pathogenic variant of the MyBPC3 gene and the factors influencing the prognosis of the disease are discussed.

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