The aims of the study were to analyze the clinical features, the penetrance and the mode of inheritance of 13 French families with dilated cardiomyopathy using diagnostic criteria recently established by a European collaboration.
Methods: Screening consisted of physical examination, ECG and Echo of all the probands first degree relatives (n = 118). Using major Echo criteria [ejection fraction (EF) < 45% or FS < 25% and left ventricular diameter (LVD) > 117% of the predictive value], or combined minor Echo/ECG criteria, relatives were classified as affected, unknown or healthy.
Results: (1) Adult affected relatives (n = 31) were identified with major Echo criteria in 74% of cases, and with combined minor Echo/ECG criteria in 26% of cases. (2) In the unknown relatives (n = 21), the most common abnormality was an isolated left ventricular dilation (67%). (3) Mode of inheritance was autosomal dominant (AD) in 11 families and possibly autosomal recessive in two. (4) In AD families, the penetrance was incomplete in adults (72%), age-related (O.R.: 1.3 per 10 years; 95% CI 1.03-1.56) and sex-related [greater in men (87%) than in women (61%), actuarial survival curve: P<0.002]. (5) Mortality related to end stage heart failure was 2.2 times as high as mortality related to sudden death (11% vs. 5%).
Conclusions: (1) In the absence of a specific phenotype of FDC, the characterization of relatives appears more accurate when minor criteria were added. (2) Since high mortality (16%) and incomplete penetrance frequently give rise to small nuclei of clinically affected and alive relatives per family, the accurate model of penetrance that we proposed might be helpful in the future to enhance the statistical power of linkage analysis in this disease.