In order to test the type of heredity and to assess further genealogical characteristics in our population the authors examined 105 families with hypertrophic cardiomyopathy. The families were subjected to clinical, electrocardiographic and echocardiographic examination of relatives (72% grade 1 relatives) as well as to a genealogical and psychological examination. For the proband's siblings the empirical risk of disease was 24%, in male probands it wts four times higher for brothers than sisters, in female probands it was three times higher in sisters. The sex ratio of six siblings in men was 20:4, in women 3:14. For children the risk was substantially higher in youner probands (under 30 years risk 40%, above 51 years 6.7%). The proband's parents were affected in 28%, fathers almost twice as frequently in male probands, and equally frequently in female probands. Fitness (reproduction fitness, f) was substantially reduced in the entire group, in isolated and familial cases and in different age groups, more in women than in men. The gene penetrance (assuming monofactorial heredity) was estimated by the method of definite carriers as 50%. Earlier manifestations (anticipation) and a more severe course of the disease was observed practically in all families with occurrence of the disease in more than 2 generations (influence of selection--sampling error). In our group the heredity in hypertrophic cardiomyopathies was not simple autosomal dominance, it was not possible to rule out heterogeny, phenocopy, sexual influence. On the other hand, the group was too small to make possible unequivocal conclusions and the data were not quite consistent with data in the literature. Genetic counselling, possibly DNA diagnosis, would be needed to elucidate heredity of this disease.

Keywords: Adult; Cardiomyopathy, Hypertrophic /epidemiology/; Child; Czechoslovakia /epidemiology/; Female; Humans; Male; Middle Aged; Risk Factors