Hypogonadism pathophysiology

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Ahmed Elsaiey, MBBCH [2]

Overview

Pathophysiology

Pathogenesis

Hypogonadism in males

  • The hypogonadism pathogenesis in males depends mainly on the testosterone deficiency. Testosterone secretion occurs as the following:
    • Testosterone is secreted in response to stimulation signals from the brain cortex to the hypothalamus. The hypothalamus by its role secrets the gonadotropin releasing hormones (GnRH).
    • GnRH stimulates the pituitary gland which by its role secretes the gonadal hormones the Follicle Stimulating Hormone (FSH) and the Luteinizing Hormone (LH).
    • In males, LH stimulates the leydig cells in the testes which produce testosterone by converting the cholesterol to testosterone.
    • Production of testosterone from the testes gives negative feed back to the pituitary. This feedback inhibit the production of FSH and LH from the pituitary.
  • Testosterone deficiency can occur when different acquired or congenital disease affect the organs responsible for its secretion. So, pathogenesis of the hypogonadism in males depends on the underlying cause.[1]
  • GnRH deficiency has a main role in hypogonadism pathogenesis in males as it leads to decrease of the gonadal hormone and deficiency of testosterone eventually.[2]
  • It has been proved that GnRH deficiency is associated with most cases of idiopathic hypogonadotrophic hypogonadism in males.

Genetic

  • Gentic mutations have a big role in development of the hypogonadism especially congenital hypogonadotropic hypogonadism. There are more than 25 genes participate in the pathogenesis of hypogonadism.[3]
  • In this table number of genes with the associated diseases causing hypogonadism are enlisted:
Associated disease Genes Mutation Associated features with the mutated gene Comments
Kalman syndrome (With loss of smelling sense - Anosmia) ANOS 1[4]
  • X - linked recessive
  • Gene deletion or point mutations
  • Anosmia
  • Renal agenesis
GnRH deficiency results from impairment of migration of the hormonal neurons to the hypothalamus in the embryological development.[5]
SOX 10
  • Autosomal dominant
  • Deafness[6]
  • Iris pigmentation
SEMA3A
  • Loss of function mutations
  • SEMA3A gene's funciton is to encode the semaphorin 3A.
  • Semaphorin 3A is important for the GnRH neurons migration.
  • Defect in SEMA3A gene will end up with GnRH deficiency.[7]
IL17RD
  • Autosomal dominant
  • Deafness
FEZF1
  • Autosomal recessive
  • Loss of function mutations
Idiopathic hypogonadotrophic hypogonadism (IHH) (Normal smelling sensation - normosmia) KISS1R
  • Gain of function mutations
  • KISS1R is important for GnRH secretion and puberty process.[8]
KISS1
  • Autosomal recessive
  • Loss of functions mutations
GNRHR
  • Loss of function mutations
  • Patients with hypogonadism due to GNRHR mutations usually do not respond properly to the exogenous GnRH.
  • On big doses of GnRH, ovulation may be initiated in some patients.
GNRH1
  • Autosomal recessive
  • GNRH1 is responsible of pre-pro GnRH encoding.[9]
TAC3
  • Autosomal recessive
  • Microcephallus
  • Cryptorchidism
  • Mutation in the pituitary - hypothalamic pathway signaling.[10]
Mixed anosmic and nosmic IHH FGFR1
  • Autosomal dominant
  • Loss of function mutations
  • Hereditary spherocytosis.
  • Cleft palate
  • Unilateral deafness
  • It has an organizational function with ANOS1.
  • Products of ANOS1 act like a co receptor for FGFR1.[11]
FGF8[12]
  • Autosomal dominant
  • Deafness
  • Cleft lip and palate
  • Osteoporosis
PROK2

PROKR2

  • Autosomal recessive
  • It has a role in the development of olfactory bulb and GnRH neurons migration.[13]

References

  1. Kumar P, Kumar N, Thakur DS, Patidar A (2010). "Male hypogonadism: Symptoms and treatment". J Adv Pharm Technol Res. 1 (3): 297–301. doi:10.4103/0110-5558.72420. PMC 3255409. PMID 22247861.
  2. Spratt DI, Carr DB, Merriam GR, Scully RE, Rao PN, Crowley WF (1987). "The spectrum of abnormal patterns of gonadotropin-releasing hormone secretion in men with idiopathic hypogonadotropic hypogonadism: clinical and laboratory correlations". J Clin Endocrinol Metab. 64 (2): 283–91. doi:10.1210/jcem-64-2-283. PMID 3098771.
  3. Boehm U, Bouloux PM, Dattani MT, de Roux N, Dodé C, Dunkel L; et al. (2015). "Expert consensus document: European Consensus Statement on congenital hypogonadotropic hypogonadism--pathogenesis, diagnosis and treatment". Nat Rev Endocrinol. 11 (9): 547–64. doi:10.1038/nrendo.2015.112. PMID 26194704.
  4. Franco B, Guioli S, Pragliola A, Incerti B, Bardoni B, Tonlorenzi R; et al. (1991). "A gene deleted in Kallmann's syndrome shares homology with neural cell adhesion and axonal path-finding molecules". Nature. 353 (6344): 529–36. doi:10.1038/353529a0. PMID 1922361.
  5. Schwanzel-Fukuda M, Bick D, Pfaff DW (1989). "Luteinizing hormone-releasing hormone (LHRH)-expressing cells do not migrate normally in an inherited hypogonadal (Kallmann) syndrome". Brain Res Mol Brain Res. 6 (4): 311–26. PMID 2687610.
  6. Pingault V, Bodereau V, Baral V, Marcos S, Watanabe Y, Chaoui A; et al. (2013). "Loss-of-function mutations in SOX10 cause Kallmann syndrome with deafness". Am J Hum Genet. 92 (5): 707–24. doi:10.1016/j.ajhg.2013.03.024. PMC 3644631. PMID 23643381.
  7. Cariboni A, Davidson K, Rakic S, Maggi R, Parnavelas JG, Ruhrberg C (2011). "Defective gonadotropin-releasing hormone neuron migration in mice lacking SEMA3A signalling through NRP1 and NRP2: implications for the aetiology of hypogonadotropic hypogonadism". Hum Mol Genet. 20 (2): 336–44. doi:10.1093/hmg/ddq468. PMID 21059704.
  8. Teles MG, Bianco SD, Brito VN, Trarbach EB, Kuohung W, Xu S; et al. (2008). "A GPR54-activating mutation in a patient with central precocious puberty". N Engl J Med. 358 (7): 709–15. doi:10.1056/NEJMoa073443. PMC 2859966. PMID 18272894.
  9. Bouligand J, Ghervan C, Tello JA, Brailly-Tabard S, Salenave S, Chanson P; et al. (2009). "Isolated familial hypogonadotropic hypogonadism and a GNRH1 mutation". N Engl J Med. 360 (26): 2742–8. doi:10.1056/NEJMoa0900136. PMID 19535795.
  10. Gianetti E, Tusset C, Noel SD, Au MG, Dwyer AA, Hughes VA; et al. (2010). "TAC3/TACR3 mutations reveal preferential activation of gonadotropin-releasing hormone release by neurokinin B in neonatal life followed by reversal in adulthood". J Clin Endocrinol Metab. 95 (6): 2857–67. doi:10.1210/jc.2009-2320. PMC 2902066. PMID 20332248.
  11. González-Martínez D, Kim SH, Hu Y, Guimond S, Schofield J, Winyard P; et al. (2004). "Anosmin-1 modulates fibroblast growth factor receptor 1 signaling in human gonadotropin-releasing hormone olfactory neuroblasts through a heparan sulfate-dependent mechanism". J Neurosci. 24 (46): 10384–92. doi:10.1523/JNEUROSCI.3400-04.2004. PMID 15548653.
  12. Falardeau J, Chung WC, Beenken A, Raivio T, Plummer L, Sidis Y; et al. (2008). "Decreased FGF8 signaling causes deficiency of gonadotropin-releasing hormone in humans and mice". J Clin Invest. 118 (8): 2822–31. doi:10.1172/JCI34538. PMC 2441855. PMID 18596921.
  13. Cole LW, Sidis Y, Zhang C, Quinton R, Plummer L, Pignatelli D; et al. (2008). "Mutations in prokineticin 2 and prokineticin receptor 2 genes in human gonadotrophin-releasing hormone deficiency: molecular genetics and clinical spectrum". J Clin Endocrinol Metab. 93 (9): 3551–9. doi:10.1210/jc.2007-2654. PMC 2567850. PMID 18559922.

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