Absence of strong linkage disequilibrium between odorant receptor alleles and the major histocompatibility complex

The odorant receptor (OR) genes constitute the largest gene family among vertebrates. While over 800 loci are present in the human genome, their allele diversity is still poorly characterized. It has been hypothesized that the products of OR genes can be relevant in the reproductive context, thereby interacting with products of genes of the major histocompatibility complex (MHC). Here we investigated the genetic diversity of the OR2W6P, OR2B8P, OR1F12 and OR12D2 genes, in order to define haplotypes and haplotype frequencies. We measured levels of linkage disequilibrium (LD) between these OR genes and the MHC genes HLA-A, HLA-B and HLA-DRB1. This was accomplished through the assessment of 30 single nucleotide polymorphisms (SNPs) in samples from 61 family trios. We characterized 26 alleles among the four OR genes and identified three SNPs that had not yet been reported. Based on our haplotype analysis, LD spanning the OR-HLA region is not very strong, and therefore not enough to enable selection regarding specific HLA-OR haplotypes.