The neuroendocrine control of reproduction in all mammals is governed by a hypothalamic neural network of approximately 1500 gonadotropin-releasing hormone (GnRH) secreting neurons that control the activity of the reproductive axis across life. Recently, the syndrome of human GnRH deficiency, either with anosmia, termed Kallmann syndrome, or with a normal sense of smell, termed normosmic idiopathic hypogonadotropic hypogonadism, has proven to be important disease models that have revealed much about the abnormalities that can befall the GnRH neurons as they differentiate, migrate, form networks, mature and senesce. Mutations in several genes responsible for these highly coordinated developmental processes have thus been unearthed by the study of this prismatic disease model. These genetic studies have opened up a new chapter in the physiology and the pharmacology of the gonadotropic axis.

ABSTRACT. We tested the hypothesis that mutations in NR5A1 and PIN1 cause disorders in gonadotropin-gonadal system development and function, throught direct DNA sequencing of the coding sequence and splice-sites of NR5A1 and PIN1 in 50 subjects with sporadic idiopathic hypogonadotropic hypogonadism. These patients were recruited from the Pediatrics section of Tongji Hospital, Tongji Medical College, in Wuhan, China. None of the affected subjects had clinical signs of adrenal insufficiency. The NR5A1 and PIN1 mutations were found in 7 of the 50 cases. These 7 individuals presented severely low serum concentrations of testosterone or of estradiol and gonadotropin. Adrenal insufficiency was not diagnosed in any of these patients. Consequently, NR5A1 and PIN1 mutations should be considered in idiopathic hypogonadotropic hypogonadism patients with normal karyotypes and without adrenal insufficiency.

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