nephropathic cystinosis

Nephropathic cystinosis is an inherited metabolic disorder characterized by the buildup of cystine crystals in body tissues, including the bone marrow, liver, cornea, and kidneys. This condition typically begins in infancy and leads to symptoms such as poor growth, excessive urination, rickets, and kidney malfunction. The crystal deposits in the kidneys cause Fanconi syndrome, a defect in the reabsorption of essential substances, eventually leading to kidney failure by about age 10 if untreated.1

The disorder is caused by mutations in the CTNS gene, which normally produces a protein that transports cystine out of cellular lysosomes. When this protein is dysfunctional, cystine accumulates. Diagnosis involves genetic testing, observing Fanconi syndrome symptoms, and detecting cystine crystals in the cornea or elevated cystine levels in cells. Treatment focuses on depleting cystine with medication, but kidney damage is irreversible, often necessitating dialysis or transplantation.1