Male-to-female sex reversal in horses is a developmental disorder in which phenotypic females have a male genetic constitution. Male-to-female sex reversal is the second most common genetic sex abnormality, after X chromosome monosomy. All male-to-female sex reversal cases studied to date have been found to be infertile. Therefore, a screening test is particularly useful in laboratories doing DNA genotyping in horses. Our laboratory has tested > 209,000 horses for parentage using a panel of microsatellite markers and the sex marker gene amelogenin (AMEL). Suspect XY sex reversal cases are reported females with a male profile by AMEL testing. After routine genotyping, 49 cases were detected and further tested using the sex-determining region Y (SRY) gene, confirming the XY SRY-negative genotype of suspect sex reversal cases. When some inconsistencies arose in the initial result, a molecular panel of X- and Y-linked markers was analyzed for these samples. Of the 49 cases, 33 were confirmed as XY SRY-negative. The remaining 16 cases were identified as false-positives as a result of anomalies of AMEL testing in horses.

马的男女性别逆转是一种发育障碍，其中表型雌性具有雄性遗传结构。男性对女性的性别逆转是仅次于 X 染色体单体的第二个最常见的遗传性性别异常。迄今为止研究的所有男性对女性的性逆转病例都被发现是不育的。因此，筛选测试在对马进行 DNA 基因分型的实验室中特别有用。我们的实验室已经使用一组微卫星标记和性别标记基因牙釉蛋白 ( AMEL )测试了 > 209,000 匹马的亲子关系。通过AMEL测试报告的疑似 XY 性逆转病例为具有男性特征的女性。常规基因分型后，检测出49例病例，并使用性别决定区Y（SRY) 基因，确认可疑性逆转病例的 XY SRY阴性基因型。当初始结果出现一些不一致时，对这些样品进行了 X 和 Y 连锁标记的分子组分析。在 49 例病例中，33 例被确认为 XY SRY阴性。由于马的AMEL测试异常，其余 16 例被确定为假阳性。