Enzyme deficiency

Kallmann syndrome

What is missing: Hypothalamic GnRH neurons.

Presentation

Puberty never starts, and the patient cannot smell

Why the signs follow

No GnRH means no FSH or LH, so puberty never begins. The smell clue comes along because GnRH neurons migrate into the brain with the olfactory neurons during development.

Written for exam preparation, not for diagnosis.

Menstrual cycle (HPG axis) All control points