Zur Genetik der Osteochondrose bei Sportpferden

The Osteochondrosis (OC) is the most important developmental disturbance of the juvenile horse and has a massive economical impact on the equine industry. It is a degenerative joint disease that occurs due to a disturbance of the enchondral ossification predominantly on fetlock, hock and stifle joints. Environmental as well as genetic factors play a key roll in the development of the disease. This paper is a summary about the current knowledge regarding the genetic background of OC. Heritability estimations for OC in populations of Warmblood and Standardbred horses revealed results from 0.1 – 0.4, but these numbers have to be evaluated critically due to partly differing methods of analyses. Calculations showed a genetic correlation close to zero or even negative. Using whole genome scans, 14 Quantitative Trait Loci (QTL) could be identified, of which the eight most important QTL were confirmed. Genome-wide association studies with single nucleotide polymorphisms (SNPs) allowed the localisation of further QTL in Warmblood, Thoroughbred and Standardbred horses. QTL in South German Coldblood horses and QTL in Hanoverian horses had corresponding locations only on the chromosomes ECA4, 5, 16 and 18. Additionally it was possible to identify several possible candidate genes for OC(D). Further studies will be neccessary both in this field and in Next Generation Sequencing (NGS) to understand molecular genetic mechanisms of the disease. In order to reduce and eliminate OC by breeding, selection schemes based on breeding values or genomic selection, can be applied