Cystinosis is a disorder leading to the accumulation of cysteine, forming crystals within body cells, particularly damaging the kidneys and eyes.
If untreated, children with cystinosis develop kidney failure around age 10. There are three forms: nephropathic cystinosis, the most severe, starts in infancy, causing poor growth, kidney disorder, and sensitivity to light due to cysteine crystals in the eyes. Symptoms also include muscle wasting, difficulty swallowing, diabetes, thyroid issues, and nervous system problems. Less severe forms may have later onset and may not impact the kidneys, varying in symptoms and severity. Cystinosis management has been significantly improved with the oral drug cysteamine (Cystagon), which reduces cysteine crystal accumulation, delaying kidney failure and enhancing growth in children. Nutritional monitoring, hydration, vitamin supplements, and growth hormone treatments are essential, while kidney transplants are a viable option, preventing cysteine crystal buildup in the new kidney but potentially affecting other organs.
Cystinosis is caused by pathogenic (disease-causing) variants in the CTNS gene and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance to have a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background. For example, individuals of Sephardic Jewish descent have a 1 in 100 chance to be a carrier.
Another name for this condition is cysteine storage disease.
Resources:
Cystinosis Research Foundation
Revised October 2023
