A COMBINATION OF KARIOTYPING AND MOLECULAR METHODS COULD INCREASE THE DETECTION ACCURACY OF CHROMOSOMAL ABNORMALITIES IN HORSES: A CASE REPORT IN PURA RAZA ESPAÑOL HORSES

MIGUEL MORENO MILLÁN; DELIA SALENO; GABRIEL ANAYA; YAMILA PIROSANTO; FLORENCIA AZCONA; OLIVIA MARCUZZI; ANTONIO MOLINA; SEBASTIAN DEMYDA PEYRÁS

Biotechnology in Animal Husbandry

Institute for Animal Husbandry, Belgrade

Lugar: Belgrado; Año: 2019

1450-9156

Chromosomal abnormalities associated with the sex-pair are a major cause of infertility in equines. This domestic species is, by far, the livestock animal in which more cases have been reported, including sex-pair mosaicisms, chimerisms and sex reversal and Turner´s syndromes. However, its karyotype is complex and therefore, the percentage of individuals with fertility problems which are chromosomally evaluated is still scarce. To this end, we recently developed a new molecular methodology based on short tandem repeats analysis which allows determining most of this abnormalities in a simple way. But its efficiency sensibility is limited in the case of mosaicisms. In this study, we combined conventional karyotyping and molecular methods, to evaluate the chromosomal complements of a seven years old mare Pura Raza Español which showed a prominent clitoris which naturally protruded by the vulva and absence of estrous. Ultrasonographic findings also showed a small uterus and bilateral ovary hypoplasia. Seven STR markers were evaluated in DNA obtained separately from blood and hair, as well as ZFXY and SRY genes by PCR and capillary electrophoresis according to our methodology. Additionally, G-banded karyotype was performed in order to determine the chromosomal complement. Molecular results showed a normal mare profile, in both DNA samples, with negative results for ZFY and SRY and positive results for ZFX. However, karyotyping revealed the presence of two cellular lines: one compatible with a normal mare (64,XX) and an additional line compatible with Turner´s syndrome (63,X) in a proportion of 70/30 respectively. In this case, the absence of differences between molecular profiles in two different DNA samples ruled out the presence of chimerism, which cannot be discarded by conventional karyotyping. Thus we determined the existence of sex-pair mosaicism (64,XX/63,X) as the cause of the mare infertility. Overall, the use of karyotyping and molecular cytogenetic technologies improve the accuracy in the detection of choromosomal abnormalities in horses.