Background: To elucidate the pathological features and genetic etiology of the testes in patients of transverse testicular ectopia (TTE) without persistent Müllerian duct syndrome (PMDS) using immunohistochemical staining and genetic analysis.

Materials and Methods: Two patients of TTE without PMDS were subjected to orchiopexy. We performed testicular biopsies during operation and obtained blood samples before the operation. Testicular tissues were stained for c-kit, PLAP, and UTF1 in order to evaluate the presence of intratubular malignant germ cells. Additionally, we performed polymerase chain reaction-based direct sequencing to identify the SNPs of genes associated with testicular descent (AMH , AMHR2 , INSL3 and RXFP2 ). The three-dimensional structures of protein were predicted using the SWISS-MODEL

Results: In immunohistochemical analysis, c-kit and UTF1 were positive, whereas PLAP was negative in three testicular tissue samples from the two patients. These features were also detected on the unaffected side. In mutation analysis, common mutations in the gene encoding AMH were g.365G>T and g.1416G>A, and g.4983G>A was commonly observed in the gene encoding INSL3 . There were eight common mutations in intronic regions and 3′ untranslated regions and one in exon 12 (g.46869A>G) of the gene encoding RXFP2 .

Conclusions: Because UTF1, a specific marker of spermatogonial stem cell activity, was expressed both in the affected side and unaffected side in the testicular tissue in two patients, it is likely that the risk of malignancy is high in these patients. Our results of mutation analysis is consistent with previous reports, and mutations in exon 1 of AMH may contribute to the etiology of TTE without PMDS.

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