INTRODUCTION AND OBJECTIVES: Cryptorchidism is found in 93% of Prader-Willi Syndrome (PWS) cases and is a criterion for the phenotype. It is associated with hypogonadism and men with PWS are thought to be infertile. To study the fertility potential in boys with PWS syndrome we analyzed testicular histology in infant boys.

METHODS: 10 boys aged 0.5-2.8 years (mean age= 1.4 yrs) with a primary diagnosis of Prader-Willi Syndrome and bilateral undescended testes (UDT) underwent orchiopexies and bilateral testis biopsies. Histologic evaluation of the testes occurred after storage in glutaraldehyde and embedding in Epon. Biopsies of the PWS UDTs are compared to age-matched (Group 1= 0-18 mos, n=228; Group 2= 19-36 mos, n=99) biopsies of bilateral UDT as controls.

RESULTS: 19/20 UDTs were palpable below the internal inguinal ring. The average total germ cells/tubule is 1.7 (0-7 TGC/T). Group1 has a TGC/T= 2.45 in PWS compared to 2.26 in UDT controls. Group 2 has a TGC/T= 0.73 in PWS compared to 0.67 in UDT controls. Ad spermatogonia are present on at least one side in 5/9 boys: 3/4 (75%) in Group 1, 2/5 (40%) in Group 2 (total 8 testes, mean = .024 Ad/T). Control UDTs show Ad spermatogonia present in 138/178 (78%) in Group 1 and 29/67 (43%) in Group 2. 7/10 PWS boys have at least 1 testis with TGC/T > 0.6. Only 1 PWS boy has complete absence of germ cells.

CONCLUSIONS: Prader-Willi Syndrome appears to be a diverse disorder with respect to testicular histology. Previous studies have shown poor histology in most boys with no reported incidence of paternity, though orchiopexies were reported in older boys. In this young cohort, most of the boys demonstrated adequate total germ cell counts with half showing evidence of maturation of the fetal gonocytes into Ad spermatogonia, similar to other UDT patients. Therefore, we recommend early orchiopexies in all boys with PWS to maximize any fertility potential.

Source of Funding: None