A Diploid-Triploid (60,XX/90,XXY) Intersex in a Holstein Heifer

The diploid/triploid (60,XX/90,XXY) condition in Bos taurus is very rare and only three cases have been published previously. The present animal exhibited an aplastic vulva, penis and clitoris agenesis, a male-like urethra located in a pseudoprepuce opening between the mammary complexes and a well developed M. rectipeninus. A normal (60,XX) female karyotype was detected in lymphocyte cultures whereas uterus and tendon cells revealed a 60,XX/90,XXY mixoploidy. Quantification of X and Y chromosome-specific sequences using RT-PCR revealed extraordinary high Y chromosome equivalents in the sample recovered from the male-like transformed vestibulum vaginae suggesting a causative relationship. The pathogenesis of the missing clitoris and penis, which is contrasted by the concomitant presence of a well developed M. rectipeninus, remains difficult to explain. A chimeric origin is suggested despite the fact that microsatellite analysis of the animal's blood cells displayed no un- usual allele accumulation.