The Use of Molecular and Cytogenetic Methods as a Valuable Tool in the Detection of Chromosomal Abnormalities in Horses: A Case of Sex Chromosome Chimerism in a Spanish Purebred Colt

SEBASTIÁN DEMYDA PEYRÁS; ALBERTO MEMBRILLO; MONIKA BUGNO PONIEWIERZKA; KLAUDIA PAWLINA; GABRIEL ANAYA; MIGUEL MORENO MILLÁN

Cordoba

Congreso; II Congreso Científico de Investigadores en Formación en Agroalimentación de la eidA3; 2013

Universidad de Córdoba

The Spanish Purebred Horse (SPB) is the most important equine breed reared in the Iberian Peninsula being recognized as a hallmark of Spanish image and traditions around the world. To prevent errors in the allocation of parentage, SPB Association has implemented a mandatory paternity test of a set of 17 Short Tandem Repeat markers (STR) to allow the entrance of every new foal in the Association´s records. This study in complemented with an exhaustive physical and morphological inspection. Foals showing abnormal results are currently submitted to chromosomal analysis to detect chromosomal abnormalities. Horse karyotype was finally standardized in 1996 consisting of 31 pairs of autosomal chromosomes and one pair of sexual chromosomes. However, cytogenetic evaluation in horses remains very scarce, usually due to the lack of interest by owners and clinical field veterinarians in these kinds of studies (Lear and Bailey 2008) or due to the difficulty to find qualified laboratories to conduct this type of analysis (Moreno-Millan et al. 2012). Normally, only infertile or sub-fertile high-valued mares or stallions that develop some kind of phenotypic alteration are karyotyped. There is actually a single large-scale cytogenetic screening performed to date in horses (Bugno et al. 2007). This lack of studies occurs despite the fact that primary infertility in phenotypically normal mares had repeatedly been associated with several sex chromosome abnormalities (Villagómez et al. 2009). By this reason a high number of cases remain undiagnosed. But even more if we consider that, a high percentage of the foals which have chromosomal aberrations show no phenotypic or clinical signs until they reach adulthood.