NORD’s Rare Disease Video Library provides brief stories from patients, parents and caregivers about living with a rare disease.
Summary
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. The kidneys and eyes are the two organs most often affected. Generally, cystinosis is broken down into three different forms known as nephropathic cystinosis, intermediate cystinosis and non-nephropathic (or ocular) cystinosis, although there is overlap among these arbitrary categories. The age of onset, symptoms and severity of cystinosis can vary greatly from one person to another. Nephropathic cystinosis begins 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. Individuals with nephropathic cystinosis and most people with intermediate cystinosis have ultimately required a kidney transplant. Non-nephropathic cystinosis affects only the corneas of the eyes, although cystine is stored in other tissues to a certain extent. Cystinosis is caused by variants in the CTNS gene and is inherited in an autosomal recessive pattern.
Introduction
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 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 people with cystinosis, the lack of this 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.
