IHH gene polymorphism among three horse breeds and its application for association test in horses with osteochondrosis.

Genetic polymorphism of IHH gene were investigated in Angloarabian, Polish Coldblood and Polish Halfbred horses with the inclusion of a group of Polish Halfbreds affected by osteochondrosis. IHH is a good candidate gene for association study of developmental disorders mainly affecting skeleton development. DNA sequence spanning IHH gene annotated in the horse genome and its putative promoter were investigated using SANGER sequencing. Analysis of genetic variability at polymorphic sites in the IHH gene body and the promoter region confirmed genetic differences between warmblood and coldblood horse breeds. A test for allelic and genotypic association at particular SNP sites revealed no association with osteochondrosis in investigated group of Polish Halfbreds. It was concluded that participation of different warmblood breeds in pedigrees of Polish Halfbreds make it difficult to search for genetic variants being associated with this complex disorder in this breed. IHH gene polymorphism investigated among three different horse populations would be valuable for further studies on equine bone developmental disorders.