A new variant of the beta subunit of the high-affinity receptor for immunoglobulin E (Fc epsilon RI-beta E237G): associations with measures of atopy and bronchial hyper-responsiveness.

The high affinity receptor for IgE (Fc epsilon RI) has a central role in mast cell degranulation and IgE mediated allergy. A systematic search through the coding regions of the beta subunit of Fc epsilon RI (Fc epsilon RI-beta) has identified a novel coding polymorphism in exon seven. An adenine to guanine substitution changes amino acid residue 237 from glutamic acid to glycine (E237G), in the cytoplasmic tail of the protein. E237G is predicted to introduce a hydrophobicity change within the C-terminus of Fc epsilon RI-beta. It is adjacent to the immunoreceptor tyrosine activation motif (ITAM), and may affect the intracellular signalling capacity of Fc epsilon RI. E237G was detected in 53 subjects from an Australian general population sample of 1004 individuals (5.3%). E237G positive subjects had a significantly elevated skin test response to grass (p = 0.0004) and house dust mite (p = 0.04), RAST to grass (p = 0.002) and bronchial reactivity to methacholine (p = 0.0009). The relative risk of individuals with E237G having asthma compared to subjects without the variant was 2.3 (95% CI 1.26-4.19; p = 0.005).