Nucleotide sequence and restriction fragment length polymorphisms of the equine C epsilon gene

IgE is the dominant immunoglobulin isotype involved in type I hypersensitiv ities in mammals. The heavy chain constant region domains of equine IgE are encoded by a single gene, the C epsilon gene. By restriction analysis of c DNA from 15 unrelated horses, we have now identified two C epsilon alleles, characterised by a Sma I restriction fragment length polymorphism, which w e designated C epsilon (a) and C epsilon (b) Sequence analvsis of both, C e psilon (a) and C epsilon (b) cDNA, showed in addition two single base excha nges resulting in two amino acid substitutions. Both sequences have only 95 .9% homology of the coding region sequence with the published equine Cc seq uence, which could represent a third haplotype. Polymorphism of the IgE hea vy chain constant region gene, as described here, might well impose genetic variability on the effector functions of equine IgE predisposition to alle rgic diseases in horses. (C) 2001 Elsevier Science B.V. All rights reserved .