Family background of respiratory atopy: a factor of serum IgE elevation in atopic dermatitis.

The incidence of family history of atopic diseases in patients with atopic dermatitis (AD) was dependent upon the number of family members. In AD patients whose family had four persons or less, the diagnostic value of atopic family history was considerably diminished. To investigate if personal or family history of atopic respiratory disease (ARD) are implicated in elevating serum IgE in AD, serum IgE values were analyzed in 200 AD patients who had a family of five or more. AD patients who had a personal or family history of ARD showed significantly higher serum IgE than AD patients who lacked both personal and family ARD history. Patients with only AD and very high serum IgE commonly had a family ARD history. Patients with severe AD and normal serum IgE mostly lacked personal and family ARD history. It appears that about 40% of total AD patients do not have predisposition for ARD.