AHH is an acquired form of the disease often occurring after sexual maturation and is not related to genetic defects. Pathogenesis
CHH is a type of HH resulting from the abnormal migration of GnRH neurons during embryonic development. GnRH neurons are derived from the olfactory placode and migrate into the central nervous system (CNS) during embryonic development. Embryonic migration can be affected by several gene mutations including but not limited to, KAL1, fibroblast growth factor (FGF8), sex determining region Y-Box 10 (SOX10), GNRHR, GNRH1 and KISS1R. Kallmann syndrome results in a loss of smell (anosmia) and is associated with KAL1 mutations. The KAL1 gene encodes anosmin-1, an extracellular adhesion molecule that plays a role in GnRH neuronal migration and adhesion. Mutated KAL1 genes leads to ill GnRH neuronal migration as well as olfactory neuron disorder causing anosmia and non-functional GnRH releasing neurons. Mutations of KAL1 are mostly nucleotide insertion or deletion causing frame shifts in the translation of anosmin-1 resulting in a faulty protein. Inactivating mutations in the genes encoding GNRH1 or its receptor will result in the failure of the HPG axis and give rise to normosmic CHH. Inactivating mutations of KISS1 or KISS1R causes normosmic CHH in humans. This is because KISS1 is the mediator for the feedback loop in the HPG axis allowing low levels of sex steroid to stimulate GnRH secretion from the hypothalamus.CHH is a genetically heterogenous disorder with cases reported as being X-linked, recessive and autosomally inherited.
In the media
April Wesson / Dr. Pimple Popper Season 2 Episode 1: “Nose No Bounds" on January 3, 2019
Olivia Buckland / Love Island 2016: After 4 years of building the courage to get it checked, the lump located near the star’s left armpit was discovered to be a lipoma, which was removed before her wedding 


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