Hypertrophic cardiomyopathy is a global disease including China

Two novel mutations of the MYBPC3 gene identified in Chinese families with hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is one of the most common genetic cardiovascular disorders. Mutations in the MYBPC3 gene are one of the most frequent genetic causes of HCM.

OBJECTIVES

To screen MYBPC3 gene mutations in Chinese patients with HCM, and analyze the correlation between the genotype and the phenotype.

METHODS

The 35 exons of the MYBPC3 gene were amplified by polymerase chain reaction in the 11 consecutive unrelated Chinese pedigrees. The sequences of the products were analyzed and the mutation sites were determined. The clinical data of genotype-positive families were collected, and the correlation between genotype and phenotype was analyzed.

RESULTS

Two mutations of the MYBPC3 gene were confirmed among 11 pedigrees. A frameshift mutation (Pro459fs) was identified in exon 17 in family H8, and a splice mutation (IVS5+5G−>C) was identified in intron 5 in family H3. These two mutations were first identified in Chinese patients with familial HCM and were absent in 110 chromosomes of healthy controls. Seven known polymorphisms were found in the cohort.

CONCLUSIONS

Compared with what was reported abroad, the MYBPC3 gene is a common pathogenic gene responsible for HCM in Chinese patients, and the phenotypes of these two mutations in their respective families may have their own clinical characteristics.

Revelation of an obstructive hypertrophic cardiomyopathy in an elderly patient

Hypertrophic cardiomyopathy (HCM) is classified as a primary cardiomyopathy. HCM is a clinically heterogeneous but relatively common autosomal dominant genetic heart disease that probably is the most frequently occurring cardiomyopathy. HCM is characterized morphologically and defined by a hypertrophied, nondilated left ventriculum (LV) in the absence of another systemic or cardiac disease that is capable of producing the magnitude of wall thickening evident (e.g., systemic hypertension, aortic valve stenosis). Most HCM patients have the propensity to develop dynamic obstruction to LV outflow under resting or physiologically provocable conditions, produced by systolic anterior motion of the mitral valve with ventricular septal contact. The phenotypic features of HCM may develop at any age from infancy to adulthood, and are characterized by a great heterogeneity in the extent, magnitude, and distribution of left ventricular hypertrophy. Hypertrophic obstructive cardiomyopathy (HOCM) often leads to heart failure, severe ischemia, severe symptoms and death. Determination of the exact site of the hypertrophy and of the obstruction of the left ventricular outflow tract, in asymmetric septal hypertrophy, establishes which is the best treatment strategy. In the treatment of HOCM, drug therapy with negatively inotropic drugs, percutaneous transluminal septal myocardial ablation by alcohol-induced septal branch occlusion, surgical myectomy and DDD pacemaker therapy are considered the therapeutical options. We present a case of an obstructive hypertrophic cardiomyopathy in an 84-year-old Italian woman with a left ventricular outflow tract (LVOT) peak gradient with the Valsalva maneuver of 188 mm Hg and with a history of first episode of syncope.