Olfactory receptors, to which odorant molecules specifically bind, are encoded by the largest gene family yet identified in the mammalian genome. We investigated additional polymorphism due to the possible existence of multiple alleles dispersed in different dog breeds, by carrying out a survey of the sequences of 16 olfactory receptor genes in a sample of 95 dogs of 20 different breeds. The level of polymorphism was high -all genes were found to have allelic variants- leading to amino-acid changes and pseudogenization of some alleles in a number of cases. This preliminary study also revealed that some alleles are breed-specific (or rare in the dog population), still some of them representing the major allele in the breeds concerned.

• Olfactory Receptor Gene Polymorphism Characteristics [ Supplementary Information : table1.xls]