kystinosis

Kystinosis is a rare, inherited metabolic disorder that affects children. It is a type of lysosomal storage disease characterized by the accumulation of cystine, an amino acid, within the body's cells. This buildup occurs because a genetic defect impairs the function of a protein responsible for transporting cystine out of the lysosomes, the cellular compartments where waste products are broken down. As cystine crystals form and accumulate, they damage various organs, including the kidneys, eyes, liver, muscles, and thyroid gland.

The symptoms of kystinosis vary depending on the severity and the specific organs affected. The most common and severe form, infantile nephropathic kystinosis, typically presents within the first year of life with failure to thrive, rickets, and kidney problems. Other complications can include light sensitivity, difficulty swallowing, and delayed growth and puberty. Milder forms may manifest later in childhood or adolescence with less severe kidney dysfunction.

Diagnosis is usually made through blood and urine tests that measure cystine levels. Genetic testing can confirm the diagnosis. Treatment focuses on managing the symptoms and preventing further complications. This often involves medications to reduce cystine levels in the body, such as cysteamine, as well as treatments for specific organ damage, such as bone supplements for rickets and eye drops for corneal crystals. Kidney transplantation may be necessary in cases of severe kidney failure. While there is no cure for kystinosis, early diagnosis and consistent treatment can significantly improve a patient's quality of life and long-term prognosis.