👤 Julia Daher Carneiro Marsiglia

Hypertrophic cardiomyopathy (HC) is the most prevalent genetic cardiac disease caused by a mutation in sarcomeres, Z-disks, or calcium-handling genes and is characterized by unexplained left ventricular hypertrophy. The aim of this study was to determine the genetic profile of Brazilian patients with HC and correlate the genotype with the phenotype. We included 268 index patients from São Paulo city and 3 other cities in Brazil and extracted their DNA from whole blood. We amplified the coding sequencing of MYH7, MYBPC3, and TNNT2 genes and sequenced them with an automatic sequencer. We identified causal mutations in 131 patients (48.8%). Seventy-eight (59.5%) were in the MYH7 gene, 50 (38.2%) in the MYBPC3 gene, and 3 (2.3%) in the TNNT2 gene. We identified 69 mutations, 24 not previously described. Patients with an identified mutation were younger at diagnosis and at current age, had a higher mean heart rate and higher nonsustained ventricular tachycardia frequency compared with those without a mutation. Patients with MYH7 gene mutations had a larger left atrium and higher frequency of atrial fibrillation than did patients with MYBPC3 gene mutations. The presence of a mutation in one of the genes suggests a worse prognosis. Mutations in the MYH7 gene, rather than in the MYBPC3 gene, were also related to a worse prognosis. This is the first work characterizing HC molecular epidemiology in the Brazilian population for the 3 most important genes. Show less

Hypertrophic cardiomyopathy (HC) is the most frequent cardiac hereditary disease, caused by mutations in sarcomere protein coding genes. Although more than 430 mutations have been identified in several continents and countries, there have been no reports of mutations in Brazil. To carry out a genetic study to identify genetic mutations that cause HC in a group of patients in Espirito Santo, Brazil. Using the SSCP technique, 12 exons from the three main genes involved in HC were studied: exons 15, 20, 21, 22 and 23 of the beta-myosin heavy chain gene (MYH7), exons 7, 16, 18, 22 and 24 of the myosin binding protein C gene (MYBPC3) and exons 8 and 9 of troponin T gene (TNNT2). 16 alterations were found, including two mutations, one of them possibly pathogenic in the MYBPC3 gene (p. Glu441Lys) and another pathogenic one, previously described in the TNNT2 gene (p.Arg92Trp), 8 rare sequence variations and 6 sequence variations with allelic frequency higher than 1% (polymorphisms). These data allow the conclusion that the genotyping of patients is feasible in our country. It is possible that the isolated p.Glu441Lys variant identified in exon 16 of the MYBPC3 gene is pathogenic, promoting a milder phenotype than that found when in association with other mutations. The p.Arg92Trp variant in the exon 9 of TNNT2 gene does not promote such a homogeneous phenotype as previously described and it can lead to severe hypertrophy. Show less