Segregation analysis of the specific response to allergens: A recessive major gene controls the specific IgE response to Timothy grass pollen

Segregation analysis of the specific response to allergens (SRA) was perfor med in a sample of 234 randomly selected Australian families using the regr essive models. Various SRA phenotypes were considered using broad and narro w definitions of these phenotypes, according to the type of test used, skin test or RAST test, and the specificity of the response to allergen. Strong evidence for familial dependencies among blood relatives was shown for mos t SRA phenotypes, especially when using a broad definition. There was no ev idence for a Mendelian factor accounting for the familial transmission of t hese broadest phenotypes, which may involve multiple factors preventing the clear detection of a major effect with Mendelian transmission. However, se gregation of a Mendelian recessive major gene was detected for one SRA sub- phenotype, the IgE response to a single allergen, Timothy grass pollen, mea sured by the RAST test. Identification of a specific SRA phenotype controll ed by a major gene may have important implications for further linkage stud ies. Genet. Epidemiol. 16:305-315, 1999. (C) 1999 Wiley-Liss, Inc.