A study of cases of rheumatic fever admitted to La Rabida Sanitarium over a 5-year period was carried out to evaluate heredity and environment as etiologic factors in rheumatic disease. The incidence of rheumatic fever was shown to be higher in families where one or both parents were known to have a positive family history of rheumatic fever. The incidence of rheumatic fever was compared in environmental groups. A totally unfavorable environment was shown to increase the incidence of rheumatic fever. No single unfavorable environmental factor changed the incidence of rheumatic fever.
The incidence of rheumatic fever in each environmental group was higher when there was a positive family history for rheumatic fever, indicating an hereditary factor in the family incidence of rheumatic fever. Analysis of the various mating types in the families with a positive rheumatic trait was carried out. Agreement with a simple autosomal recessive gene inheritance was obtained in families where both parents had a definite family history, but no agreement was obtained in cases where only one parent gave a positive family history.
