Molecular and cytogenetic studies in a case of xx sry-negative sex reversal in an arabian horse

An 18-month-old Arabian foal characterized by a stallion-like appearance was submitted for cytogenetic and molecular genetic examinations due to abnormalities of external genitalia and the presence of ovotestis-like structures in the abdominal cavity. By RB-banding the animal showed the normal female equine karyotype (2n=64, XX). Molecular analysis revealed the absence of the SRY and ZFY genes and the presence of ZFX, a typical female equine condition. The entire RSPO1 coding region was examined to exclude its involvement. Although a SNP was found in exon 3, it was not responsible for an amino acid substitution.