Familial occurrence of atopic disease: genetic versus environmental factors.

Cumulative life prevalence of atopic disease (any of reported symptoms of asthma/wheezy bronchitis, allergic rhinitis, eczema and urticaria) was studied by means of a questionnaire in 19814 (7-, 10- and 14-year-old) Swedish school children and their parents. Maternal history was found to be twice as common as paternal history. The children of affected mothers contracted atopic disease in the same proportion as the children of affected fathers yielding twice as many affected children with affected mothers than with affected fathers. The strongest parental influence on childhood disease was seen for multiple symptoms and for congruent symptoms with both parents. The number of children with both parents affected was 1.6 times larger than expected. A possible dose-response effect in polygenic inheritance is discussed as well as assumed impact of environmental factors with a tendency to familial clustering.