Testicular seminoma in a patient with a constitutively activating mutation of the luteinizing hormone/chorionic gonadotropin receptor.

A white man who had been diagnosed, 35 years previously at the age of 27 months, to have precocious puberty, was later determined to have familial male-limited precocious puberty (FMPP), on the basis of his family history, increased serum testosterone, prepubertal concentrations of follicle stimulating hormone and luteinizing hormone, and Leydig cell hyperplasia. Recently, this diagnosis was confirmed by molecular genetic analysis that demonstrated the presence of a heterozygous constitutive activating mutation of the luteinizing hormone/chorionic gonadotropin receptor. This dominant gain-of-function Asp578Gly mutation has been shown constitutively to activate the receptor in the absence of the agonist, leading to enhanced synthesis of cAMP and, in turn, to increased, sustained production of testosterone. In 1994, this patient was found to have a testicular seminoma. He represents the first case of a testicular germ cell tumor described in an FMPP patient, raising the possibility of a potentially harmful effect of prolonged increased concentrations of sex hormones, with onset early in life, upon the cellular components of the testes.