Cystinosis is a condition where cystine — a building block of proteins — builds up and forms crystals in the cells. These crystals cause damage in many organs and tissues, especially the kidneys and the eyes. It also affects the muscles, thyroid, pancreas, and testes.
There are three types of the condition, which develop at different times and have differing effects. Nephropathic cystinosis begins in infancy and causes stunted growth and kidney damage. If untreated, it causes kidney failure by age ten.
Intermediate cystinosis has the same symptoms but occurs later, usually in adolescence, with likely kidney failure in late teens to mid-twenties if untreated.
Ocular cystinosis does not affect the kidneys, but typically causes photophobia — light sensitivity — due to cystine crystal buildup in the cornea.