[Sarcoidosis and heredity. 3 familial cases].
It is very uncommon to find several cases of sarcoidosis in the same family. In the majority of published reports, only 2 persons are involved in each family. Genetic predisposition is probably, but its true importance as compared with environmental conditions is uncertain owing to the lack of epidemiology studies. We report 3 cases of sarcoidosis in the same family. In 2 of these cases (2 black sisters) the clinical set up was similar, consisting of multivisceral sarcoidosis involving the lung and mediastinum, the skin and the peripheral lymph nodes and muscles, with poor general condition and dependence on, or resistance to corticosteroids. Although the two sisters lived in different countries for several years and despite the 4-year age difference between them, the disease began in both cases at the age of 40 years. The history of this family is exemplarily in favour of a genetic predisposition and suggests than the penetrance of genetic transmission is underevaluated. Systematic pulmonary clinical and radiological examinations performed in the relatives of patients with sarcoidosis might provide information on the true incidence of familial cases. Studies of the genetic equipment of these familial cases would perhaps constitute a line of research aimed at determining the pathogenesis of the disease.