SRY-negative, 64,XX sex reversal in a Konik Polski horse: a case report

A three-years old Konik Polski (Polish Primitive Horse) individual was diagnosed as having XX sex reversal syndrome on the basis of female karyotype 64,XX, and the presence of two inter-abdominal testes and ambiguous external genitals The individual exhibited aggressive, stallion-like behaviour. The PCR analysis of the SRY gene revealed the absence of the Y chromosome sequences SRY in DNA extracted from blood, gonads, skin and liver. This is the first reported case of an SRY-negative XX- male sex reversal in a Konik Polski horse suggesting that it is sporadic case rather and not a familial occurrence.