2. Decreased level gonadotropins
3. Hyposmia or anosmia
Embryologically, GnRH (gonadotropins) neurons develop in the nose and migrate up the olfactory nerves and then through the brain to the hypothalamus. If neurons do not develop congenitally and reach hypothalamus then pubertal maturation of gonads do not occur.
It is more common in men. Mutation of the KALIG1 gene. a gene on the X chromosome that codes for an adhesion molecule necessary for the normal development of the olfactory nerve. In women, this disease can be due to other genetic abnormalities.