[Effect of heredity and environment in immune diseases. Presentation of twin data].

BACKGROUND: The study of twins is an important and informative tool in the investigation of the influence of genetic and environmental factors on the pathogenesis of familial traits.

MATERIAL: Seven diseases were analysed by carrying out an intensive study of the literature to search for concordance of monozygotic and dizygotic twins. Apart from single case studies, large unselected series have been reported, some of which show considerable differences in concordance rates. Data from twins were collected for myasthenia gravis, systemic lupus erythematosus, rheumatoid arthritis and type 1 diabetes mellitus, Crohn's disease and, for comparative purposes, also type 2 diabetes mellitus.

RESULTS: On the basis of the above-mentioned calculated concordance rates, differences in the influence of genetic factors were established, which may be of importance for the genetic counselling of affected families. These findings based on twins also confirm the multifactorial inheritance model.