NORD’s Rare Disease Video Library provides brief stories from patients, parents and caregivers about living with a rare disease.
Cystinosis is a rare, multisystem genetic disorder characterized by the accumulation of an amino acid called cystine in different tissues and organs of the body including the kidneys, eyes, muscles, liver, pancreas and brain. Generally, cystinosis is broken down into three different forms known as nephropathic cystinosis, intermediate cystinosis and non-nephropathic (or ocular) cystinosis. The age of onset, symptoms, and severity of cystinosis can vary greatly from one person to another. Nephropathic cystinosis presents in infancy and is the most common and severe form. Early detection and prompt treatment are critical in slowing the development and progression of symptoms associated with cystinosis. The kidneys and eyes are the two organs most often affected. Individuals with nephropathic or intermediate cystinosis ultimately require a kidney transplant. Non-nephropathic cystinosis only affects the corneas of the eyes. Cystinosis is caused by mutations of the CTNS gene and is inherited as an autosomal recessive disease.
Cystinosis was first described in the medical literature in 1903 by Abderhalden. Cystinosis is classified as a lysosomal storage disorder. Lysosomes are membrane bound compartments within cells that break down certain nutrients such as fats, proteins and carbohydrates. Lysosomes are the primary digestive unit within cells. Some enzymes within lysosomes break down (metabolize) these nutrients, while other proteins transport the leftover metabolic products (such as cystine) out of the lysosome. In the case of cystinosis, the lack of such a specific transporter causes cystine to accumulate in lysosomes of cells throughout the body. Cystine forms crystals (crystallizes) in many types of cells and slowly damages affected organs.