A myomesin mutation associated with hypertrophic cardiomyopathy deteriorates dimerisation properties.

Myomesin plays an important structural and functional role in the M-band of striated muscles. The C-terminal domain 13 of myomesin dimerises and forms antiparallel strands which cross-link neighboring Myosin filaments and titin in the M-line of the sarcomeres. These interactions stabilise the contractile apparatus during striated muscle contraction. Since myomesin is an important component of the M-band we screened the myomesin gene for genetic variants in patients with hypertrophic cardiomyopathy (HCM). We identified the missense mutation V1490I in domain 12 of myomesin in a family with inherited HCM. Analytical ultracentrifugation experiments, circular dichroism spectra, and surface plasmon resonance spectroscopy of myomesin fragments were carried out to investigate the effects of the mutation V1490I on structure and function of myomesin domains 11-13 and 12-13. Both the wild type and mutated myomesin domains My11-13 revealed similar secondary structures and formed stable dimers. Mutated myomesin domains My11-13 and My12-13 dimers revealed a reduced thermal stability and a significantly decreased dimerisation affinity, showing disturbed functional properties of V1490I mutated myomesin. However, monomeric myomesin domains My11-12, i.e. without dimerisation domain 13 showed no difference in thermal stability between wild type and V1490I mutated myomesin. In conclusion, the V1490I mutation associated with HCM lead to myomesin proteins with abnormal functional properties which affect dimerisation properties of myomesin domain 13. These effects may contribute to the pathogenesis of HCM.

Sudden death in hypertrophic cardiomyopathy: old risk factors re-assessed in a new model of maximalized follow-up.

AIMS: in hypertrophic cardiomyopathy (HCM), the following five risk factors have a major role in the primary prevention of sudden death (SD): family history of SD (FHSD), syncope, massive wall thickness (MWTh) >30 mm, non-sustained ventricular tachycardia (nsVT) in Holter monitoring of electrocardiography, and abnormal blood pressure response to exercise (aBPRE). In HCM, as a genetic cardiac disease, the risk for SD may also exist from birth. The aim of the study was to compare the survival curves constructed for each of the five risk factors in a traditional follow-up model (started at the first presentation of a patient at the institution) and in a novel follow-up model (started at the date of birth). In an additional analysis, we compared the survival rate in three subgroups (without FHSD, with one SD, and with two or more SDs in a family). METHODS AND RESULTS: a total of 1306 consecutive HCM patients (705 males, 601 females, mean age of 47 years, and 193 patients were <18 years) evaluated at 15 referral centres in Poland were enrolled in the study. In a novel method of follow-up, all the five risk factors confirmed its prognostic power (FHSD: P = 0.0007; nsVT: P < 0.0001; aBPRE: P = 0.0081; syncope: P < 0.0001; MWTh P> 0.0001), whereas in a traditional method, only four factors predicted SD (except aBPRE). In a novel model of follow-up, FHSD in a single episode starts to influence the prognosis with a delay to the fifth decade of life (P = 0.0007). Multiple FHSD appears to be a very powerful risk factor (P < 0.0001), predicting frequent SDs in childhood and adolescence. CONCLUSION: the proposed concept of a lifelong calculated follow-up is a useful strategy in the risk stratification of SD. Multiple FHSD is a very ominous risk factor with strong impact, predicting frequent SD episodes in the early period of life.

[Hormonal replacement therapy and selective estrogen receptor modulators in prevention of cardiovascular disease]. / Hormonalna terapia zastepcza i modulatory receptorów estrogenowych w prewencji chorób ukladu krazenia.

Postmenopausal women are at higher risk of cardiovascular disease because of increased prevalence of major coronary artery disease risk factors. The protective activity on cardiovascular system of estrogen was postulated. The data from many studies indicate favourable effect of estrogen replacement therapy. However prospective, randomized clinical trials have not proved protective influence of hormonal replacement therapy (HRT) on cardiovascular system. Moreover it was found to increased the risk of cardiovascular disease events. This article presents mechanism of estrogens activity and results of major clinical trials concerning hormonal replacement therapy. Activity of selective estrogen receptor modulators (SERMs) was also described.

Prevalence of cardiac beta-myosin heavy chain gene mutations in patients with hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is a frequent, autosomal-dominant cardiac disease and manifests predominantly as left ventricular hypertrophy. Mutations in the cardiac beta-myosin heavy chain gene (MYH7) are responsible for the disease in about 30% of cases where mutations were identified. We clinically evaluated a large group of 147 consecutive HCM patients from three cardiology centers in Germany, Poland, and Kyrgyzstan according to the same protocol. The DNA of the patients was systematically analyzed in the whole coding region of the MYH7 gene using PCR, single-strand conformation polymorphism analysis, and automated sequencing. Eleven different missense mutations (including seven novel ones) in 11 unrelated patients were identified, showing a mutation frequency of 7.5% in the study population. We further examined the families of five patients (three of German, one of Polish, and one of Kyrgyz origin) with 32 individuals in total. We observed a clear, age-dependent penetrance with onset of disease symptoms in the fourth decade of life. Genotype-phenotype correlations were different for each mutation, whereas the majority was associated with an intermediate/malign phenotype. In conclusion, we report a systematic molecular screening of the complete MYH7 gene in a large group of consecutive HCM patients, leading to a genetic diagnosis in 38 individuals. Information about the genotype in an individual from one family could be very useful for the clinician, especially when dealing with healthy relatives in doubt of their risk about developing HCM. The increasing application of genetic screening and the increasing knowledge about genotype-phenotype correlations will hopefully lead to an improved clinical management of HCM patients.