Morphogenetic targets and genetics of undescended testis.

Although important advances in testicular physiology have been achieved, the aetiology of human cryptorchidism remains mostly unknown. Next to sex steroidal signaling pathways, morphogenetic genes are specifically involved in the testicular descent via gubernacular development. Mutations in the human genes encoding insulin-like factor 3 (INSL3) and its Leu-rich repeat-containing G protein-coupled receptor 8 (LGR8), homeobox A10 (HOXA10), zinc finger 214 (ZNF214) and 215 (ZNF215) have occasionally been identified but do not seem to be a frequent cause of cryptorchidism. On the other hand, common polymorphisms in these genes have recently been investigated as contributing risk factors for idiopathic isolated (nonsyndromic) cryptorchidism.