[Geographical pathology and genetic markers: detection of associations (author's transl)].

The study of potential associations between genetic markers and various diseases is an important approach in epidemiology. With such studies it is possible to reveal an hereditary component for multifactorial diseases. There are three kinds of analyses: --comparisons of the frequency of the marker in patients and in a control group; --investigations of genetic markers in families with high incidence of disease; --studies of geographical clines between the incidence of the disease and the marker frequency. The interpretation of such geographical associations is difficult. These associations can be the reflect of the migration of susceptibility genes with genetic markers. The HLA system is the better for this kind of approach.