Testicular Histology in Boys With Prader-Willi Syndrome: Fertile or Infertile?

PURPOSE: Prader-Willi syndrome is associated with hypogonadism. Cryptorchidism is found in 93% of cases and considered a phenotypic criterion. Men with Prader-Willi syndrome are thought to be infertile. To study the fertility probability in boys with Prader-Willi syndrome we analyzed testicular histology in 8 prepubertal boys and 1 man. MATERIALS AND METHODS: Eight boys 16 months to 14 years old with a proven molecular diagnosis of Prader-Willi syndrome, including 6 with a deletion on chromosome 15 and 2 with uniparental maternal disomy of chromosome 15, underwent orchiopexy and the man underwent unilateral orchiectomy. Prepubertal testes were classified into 4 Nistal categories according to mean tubular diameter, the tubular fertility index (average percent of tubules containing spermatogonia) and the Sertoli's cell index. RESULTS: Two of 8 prepubertal boys showed a favorable Nistal score of I, 1 showed a Nistal score of II and 5 showed a Nistal score of III. The testis in the man showed diffuse tubular atrophy with tubular hyalinization, a Sertoli's cell nodule, vacuolized Leydig cells, peritubular hyalinization and small tubuli. CONCLUSIONS: Prader-Willi syndrome appears to be a heterogenic disorder with respect to testicular histology. Although most boys showed absent spermatogonia, 2 of 8 had normal testicular histology. Therefore, it is suggested that it is uncertain what the fertility outcome is in boys with Prader-Willi syndrome.