01679nas a2200277   4500000000100000000000100001008004100002260007000043653001700113653002200130653002300152100001300175700001200188700001600200700001300216700001200229700001300241700001100254700001200265245010600277250000800383300001200391490000800403520097600411022001401387       2015                            d  c07/2015bSchlütersche Verlagsgesellschaft mbH & Co. KGaHannover10aThoroughbred10aXY testicular DSD10ahorse racing sport1 aC Dierks1 aH Sieme1 aM Piechotta1 aS Lehner1 aJ Merkt1 aH Uphaus1 aE Klug1 aO Distl00aElevated testosterone levels in a racing horse due to an XY testicular disorder of sexual development  a7/8  a335-3390 v1283 aA female thoroughbred successful in horse racing was positively tested for high testosterone values. This horse neither showed stallion-like-behaviour nor signs of ambiguous external genitalia. The karyotype of this horse was 2n=64,XY and the sex-determining region of Y (SRY) PCR was positive. Hair samples tested for naturally testosterone revealed values normal for stallions, and tests for eight synthetic testosterone esters remained negative. The phenotype, ultrasonographic examination, hormone status, cytogenetic evaluation and molecular diagnostics lead to the diagnosis of an XY testicular disorder of sexual development (DSD) due to a complete androgen insensitivity syndrome. To our knowledge this is the first report about a thoroughbred in racing sports with an XY testicular disorder of sexual development. To date, intersex racing horses have never been described in thoroughbreds or a regulation for intersexes in regard to horse races has been issued.   a0005-9366