Identification of a novel single-nucleotide polymorphism (Val554Ile) and definition of eight common alleles for human IL4RA exon 11.

The interleukin (IL)-4 receptor alpha chain gene (IL4RA) is a polymorphic gene which is reportedly involved in the development of atopy. Of the 14 single-nucleotide polymorphisms (SNP) reported to date in the coding region of IL4RA, 11 are positioned to exon 11. This big exon encodes more than two thirds of the mature protein, including most of the cytoplasmic region. Here we report the identification of a new IL4RA SNP at the first nucleotide of codon 554 (GTA --> ATA) in exon 11, leading to an amino acid substitution from Val to Ile (V554I). Furthermore, we present complete nucleotide sequence data for eight common alleles resulting from combinations of 9 out of the 12 SNP at IL4RA exon 11. Homo- or heterozygous combinations of these eight alleles accounted for all the IL4RA exon 11 genotypes found in Caucasian individuals from our geographical area.