Reproduction, smell, and neurodevelopmental disorders: genetic defects in different hypogonadotropic hypogonadal syndromes

• Published in: Frontiers in endocrinology (Lausanne) 2014-01, Vol.5, p.109-109
• Main Authors: Valdes-Socin, Hernan, Rubio Almanza, Matilde, Tomé Fernández-Ladreda, Mariana, Debray, François Guillaume, Bours, Vincent, Beckers, Albert
• Format: Article
• Language: English
• Subjects: Endocrinologie, métabolisme & nutrition; Endocrinology; Endocrinology, metabolism & nutrition; Genetics; Human health sciences; Hypogonadism; hypogonadotropic hypogonadism; Kallman syndrome; Kallmann Syndrome; kisspeptin; Kisspeptins; Leptin; male; olfaction; Olfaction Disorders; reproduction; Sciences de la santé humaine
• ISSN: 1664-2392; 1664-2392
• DOI: 10.3389/fendo.2014.00109

The neuroendocrine control of reproduction in mammals is governed by a neural hypothalamic network of nearly 1500 gonadotropin-releasing hormone (GnRH) secreting neurons that modulate the activity of the reproductive axis across life. Congenital hypogonadotropic hypogonadism (HH) is a clinical syndrome that is characterized by partial or complete pubertal failure. HH may result from inadequate hypothalamic GnRH axis activation, or a failure of pituitary gonadotropin secretion/effects. In man, several genes that participate in olfactory and GnRH neuronal migration are thought to interact during the embryonic life. A growing number of mutations in different genes are responsible for congenital HH. Based on the presence or absence of olfaction dysfunction, HH is divided in two syndromes: HH with olfactory alterations [Kallmann syndrome (KS)] and idiopathic hypogonadotropic hypogonadism (IHH) with normal smell (normosmic IHH). KS is a heterogeneous disorder affecting 1 in 5000 males, with a three to fivefold of males over females. KS is associated with mutations in KAL1, FGFR1/FGF8, FGF17, IL17RD, PROK2/PROKR2, NELF, CHD7, HS6ST1, FLRT3, SPRY4, DUSP6, SEMA3A, NELF, and WDR11 genes that are related to defects in neuronal migration. These reproductive and olfactory deficits include a variable non-reproductive phenotype, including sensorineural deafness, coloboma, bimanual synkinesis, craniofacial abnormalities, and/or renal agenesis. Interestingly, defects in PROKR2, FGFR1, FGF8, CHD7, DUSP6, and WDR11 genes are also associated with normosmic IHH, whereas mutations in KISS1/KISSR, TAC3/TACR3, GNRH1/GNRHR, LEP/LEPR, HESX1, FSHB, and LHB are only present in patients with normosmic IHH. In this paper, we summarize the reproductive, neurodevelopmental, and genetic aspects of HH in human pathology.