RESUMO
The present genetic study has been conducted on 29 patients with myotonic dystrophy. The diagnosis of Steinert-Batten-Gibbs disease was made by anamnestic, clinical and laboratory procedures. Six families from Istria were examined in which genealogical study was carried out through five generations. Consanguinity was observed in one family. The frequency of myotonic dystrophy, correlative features and mortality was determined for each family. The incidence of myotonic dystrophy and correlative features among the first-, second-, and third-degree relatives of patients examined was determined. We conclude that the disease occurred far more frequently in families of patients with myotonic dystrophy (8 to 33%) than in the population in general (0.017%) and that it is significantly maintained among the first-, second-, and third-degree relatives.