Genetic Variability of the High-affinity IgE Receptor?Subunit (Fc?RI?) is Related to Total Serum IgE levels in Allergic Subjects

Known susceptibility genes to atopy and asthma have been identified by linkage or associations with clinical phenotypes, including total serum IgE levels. IgE-mediated sensitivity reactions require a high-affinity IgE re-ceptor (FcεRI), which immobilizes the immunoglobulin on the surface of the effector cells, mostly mast cells and basophils. In this mini-review, recent findings are presented on genetic variation of this receptor, as related to atopy. Transcription of FCER1A gene encoding the receptor α subunit can be initiated from two separate pro-moters, the proximal one and the distal one, which results in a transcript containing two novel untranslated ex-ons (1A, 2A). Our knowledge on the role of this mechanism in allergic diseases is still at an infancy stage. Within regulatory elements of FCER1A some common single nucleotide polymorphisms have functional asso-ciations, which were recently reported and replicated in different ethnical groups. Interestingly, these associa-tions do not confer susceptibility to allergic diseases, but rather modulate serum concentrations of IgE. Similarly to the previously investigated β subunit of the receptor, FCER1A is a good candidate for a quantitative trait lo-cus (QTL) in allergic diseases, and appears to participate in the systemic regulation of IgE levels