A malignant phenotype of hypertrophic cardiomyopathy caused by Arg719Gln cardiac beta-myosin heavy-chain mutation in a Chinese family

• Published in: Clinica chimica acta 2001-08, Vol.310 (2), p.131-139
• Main Authors: Huang, Xiaohong, Song, Lei, Ma, Ai-Qun, Gao, Jinhua, Zheng, Weiyue, Zhou, Xianliang, Zhang, Qian, Lu, Hao, Li, Yuxin, Liu, Yanling, Hui, Rutai
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Amino Acid Sequence; Base Sequence; Biological and medical sciences; Cardiology. Vascular system; Cardiomyopathy, Hypertrophic - genetics; Child; China; DNA - genetics; Female; Gene mutation; Heart; Humans; Hypertrophic cardiomyopathy; Male; Medical sciences; Middle Aged; Mutation, Missense; Myocarditis. Cardiomyopathies; Myosin Heavy Chains - genetics; Pedigree; Phenotype; Polymerase chain reaction; Polymorphism, Single-Stranded Conformational; Single-strand conformation polymorphism; β-Myosin heavy chain
• ISSN: 0009-8981; 1873-3492
• DOI: 10.1016/S0009-8981(01)00538-1

Mutations of the cardiac β-myosin heavy-chain (β-MHC) gene cause hypertrophic cardiomyopathy (HCM). Recent genotype–phenotype correlation studies have shown that mutations carry prognostic significance. We studied five unrelated Chinese families with hypertrophic cardiomyopathy. Exons 3–27 and 40 of the β-MHC gene were screened with both the polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) method and the cycle sequencing of the PCR products. A previously reported heterozygous mutation Arg719Gln (arginine→glutamine in codon 719) in exon 19 was found in one family. The proband is a 30-year-old female diagnosed at age of 25 years when she presented with symptoms of chest pain, palpitations, and frequent incidents of dizziness and syncope. A two-dimensional echocardiogram showed moderate asymmetrical septal hypertrophy with left atrial enlargement. There was no obstruction of the left ventricular outflow tract (LVOT). The patient also developed atrial fibrillation. The proband's mother and one of her sisters had similar clinical manifestations and both died suddenly at the age of 38 years. In addition, two silent nucleotide substitutions (ACT63ACC, TTT244TTC) in the cardiac β-MHC gene were identified in the other four families. These synonymous mutations did not cosegregate with the disease in the families and they were also present in the 60 healthy and age-matched control subjects. Of the five families studied, we did not find any missense mutation in the remaining four families. The missense mutation Arg719Gln found in the Chinese family is associated with a malignant phenotype of severe clinical symptoms and poor survival prognosis. This mutation also causes atrial enlargement and atrial fibrillation. Our study provides further evidence that the mutation, which alters the charge of the myosin heavy chain, is associated with a serious clinical outcome.