What is cystinosis?
Cystinosis is a genetic condition in which an amino acid called cystine builds up in the cells of the body as a result of changes or mutations in a gene called CTNS. Due to these CTNS gene mutations, people with cystinosis lack enough of an enzyme called cystinosin. Cystinosin helps move, or transport, cystine out of the cells. If people lack this enzyme or if the enzyme doesn't work properly, then cystine will build up in the cells. As cystine builds up it forms crystals which interrupt cell function leading to early cell death and organ damage.
Although any muscle can be damaged by high levels of cystine,the kidneys and eyes are most often affected in people with cystinosis. The liver, muscles, pancreas, and brain are also commonly affected. Cystinosis can be very different in how it affects people. Three different forms have been identified: nephropathic cystinosis, about 95% of people who have cystinosis have this form; juvenile nephropathic cystinosis, about 3% of people with cystinosis have this form; and non-nephropathic cystinosis. Even within each type of cystinosis people will have different health problems and speed of disease progression.
There are FDA approved treatments for cystinosis; however, it is important to diagnose and treat cystinosis early to slow down the disease and have the best health outcomes. Doctors treat the disorder with drugs that lower the levels of cystine in the body and specifically in the eyes. Even with treatment, most people who have nephropathic or intermediate cystinosis will eventually need a kidney transplant.
Nesterova G, Gahl WA. Cystinosis: the evolution of a treatable disease. Pediatr Nephrol. 2013;28(1):51-59. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3505515/ Accessed March 22, 2016.
Nesterova G, Gahl WA. Cystinosis. GeneReviews website. http://www.ncbi.nlm.nih.gov/books/NBK1400/ Updated January 30, 2014. Accessed March 22, 2016.