128. A disease can slow down or even prevent puberty

There’s a disease that can slow down or even prevent puberty.

Kallmann syndrome or Kallmann’s syndrome is a dysfunction of the endocrine system. The hypothalamus fails to produce Gonadotropin-releasing hormone (GnRH), so your body doesn’t develop secondary sexual characteristics. These would include vocal changes, pubic hair and other body hair, enlargement of the genitals, development of breasts for women, and redistribution of muscle tissue for men. 

Left untreated, people with Kallmann’s syndrome will be infertile. Treatment involves using hormone replacement therapy to induce puberty artificially. Even with treatment, Kallmann’s syndrome sufferers tend to lose their ability to smell.