[Genetic epidemiology: epidemiology, genetics or none of them?]

In an attempt to contribute to a better understanding of the identity of Genetic Epidemiology, we review its conception, its field of influence, its appropriate methods and techniques and, at last, some of its applications. Genetic Epidemiology involves the study of genetic factors acting on diseases and on their environmental interactions. These includes two major areas: a descriptive one, related to the distribution of such conditions in families and populations, to the epidemiologic surveillance and to the study of determinants; and another characterized by intervention, which is related to preventive measures. Because of the difficulty in considering all possible situations, especial attention is given to review some converging epidemiological and genetical methods and techniques. Among them, we stress the case studies on lab methodologies, as dermatoglyphics, and on quantitative procedures, as path analysis. Some studies are taken as examples for application, since they have been object of research in our country: leprosy, hydrargyrism and schizophrenia.