A twin study of perfume-related respiratory symptoms.

Respiratory symptoms from environmental perfume exposure are main complaints in patients with multiple chemical sensitivities and often coincide with asthma and or eczema. In this population-based twin study we estimate the heritability of respiratory symptoms related to perfume and if co-occurrences of the symptoms in asthma, atopic dermatitis, hand eczema or contact allergy are influenced by environmental or genetic factors common with these diseases. In total 4,128 twin individuals (82%) responded to a questionnaire. The heritability of respiratory symptoms related to perfume is 0.35, 95%CI 0.14-0.54. Significant associations (p<0.05) between perfume-related respiratory symptoms and asthma, atopic dermatitis, hand eczema or contact allergy are not attributable to shared genetic or shared environmental/familial factors, except possibly for atopic dermatitis where genetic pleiotropy with respiratory symptoms to perfume is suggested by an estimated genetic correlation of 0.39, 95%CI 0.09-0.72.