A family study of atopic dermatitis. Clinical and genetic characteristics of 188 patients and 2,151 family members.

The history of 188 caucasian patients with atopic dermatitis (AD) and of 2,151 family members has been analyzed. Of the AD patients 48% suffered from respiratory atopy (36% rhinitis, 28% asthma, and 15% both). AD showed by far the earliest onset of all atopic diseases: 50% of our patients had skin lesions before the age of 2 years and 60% before the age of 5 years. In contrast, symptoms of allergic asthma developed in 40% of AD patients before the age of 5 years in comparison with only 25% who had allergic rhinitis. AD affects females more frequently than males (male to female ratio 1:1.5), regardless of whether additional respiratory atopies are present or not. In contrast, respiratory atopies develop more frequently in males than in females (male to female ratio 1.5:1). Mothers with respiratory atopy more often have atopic children (26%) than do fathers with respiratory atopy (13%). Finally, risk figures for genetic counselling are given. In short, the general risk of developing AD (3%) and atopy (7%) increases by a factor of two with each first-degree family member already suffering from atopy.