Equine Sarcoids (ES), a common form of semi-malignant skin tumor, has long been recognized as having a genetic component, but how it’s passed to offspring wasn’t fully understood. Recently, a team of researchers conducting a whole-genome scan successfully located chromosomal regions associated with ES, bringing us one step closer to understanding the causes of this disease.

"This study is still mostly preliminary, but it is the first of its kind using a whole genome scan approach for ES," said Vendula Jandova, DrMedVet, of the Swiss Institute of Equine Medicine, University of Berne and ALP-Haras, Switzerland.

This study’s subjects consisted of 222 Swiss Warmbloods from two half-sibling sire families; 26 of the subjects were affected with ES. Researchers genotyped all horses in study with 315 microsatellite markers; a phenotype (visual) grading scale classified horses as unaffected, mildly affected, or severely affected with ES. Using quantitative trait locus (QTL) statistical analysis, which correlates genotypic molecular markers and phenotypic observable traits, researchers identified chromosomal regions containing genetic variants that could contribute to ES susceptibility, including genes for regulating immune response and virus replication. Specifically, QTL data identified significant signals on equine chromosome (ECA) 20, 23, and 25.

"Our results support the hypothesis that ES is a polygenic disease with a genetic background," explained Jandova. Nevertheless, Jandova noted further study is warranted, including more exact genetic methods on larger heterogenic horse populations; on related horse populations with a high prevalence of ES; and to understand the pathogenesis of ES (the exact role of genetics, the role of the environment, and the interactions between the two)