Regulation of spermatogenesis in McCune–Albright syndrome: lessons from a 15-year follow-up.

ContextMcCune–Albright syndrome (MAS) is a disorder caused by a post-zygotic gain-of-function mutation in the gene encoding the Gs-α protein. Sexual precocity, common in girls, has been reported in only 15% of boys, and little is known on the long-term evolution of MAS in males.ObjectiveIn a boy with MAS, we studied spermatogenesis, testis histology, and immunohistochemistry with the aim to shed light on seminiferous tubule activity.DesignA boy who presented at the age of 2.9 years with sexual precocity, monolateral macroorchidism, increased testosterone levels, and suppressed gonadotropins was followed up until the age of 18.ResultsThroughout follow-up testicular asymmetry persisted and gonadotropin and testosterone pattern did not change. At the age of 18, inhibin B was undetectable while α-immunoreactive inhibin was within normal range. Anti-Mullerian hormone level was slightly subnormal. Sperm cells were 3 900 000 per ejaculate. Histology of both testes showed spermatogonia, spermatocytes, and, in some tubes, matured spermatozoa. Sertoli cells were markedly stained with anti-inhibin α-subunit antibody in both the testes. There was no immunostaining of Sertoli, Leydig, or germ cells with anti-βA or anti-βB antibody. MAS R201H mutation was identified in both the testes.ConclusionThe 15-year follow-up in this boy with MAS demonstrated that autonomous testicular activation and gonadotropin suppression persisted over time. This provides an interesting model of active spermatogenesis despite long-term FSH suppression. It also suggests that FSH is needed for the full expression of the inhibin βB-subunit gene, an expression previously reported in the germ and Leydig cells of normal adult subjects.