What is Cystinosis?
Cystinosis is an inherited disease that causes the amino acid cysteine to accumulate within body cells and form crystals which can damage the body’s organs, particularly the kidneys and eyes. Without treatment, children with the condition will experience kidney failure around the age of 10.
There are three forms of cystinosis. The most severe form, nephropathic cystinosis, appears in infants. It causes poor growth and renal tubular Fanconi syndrome, a kidney disorder in which the organ eliminates certain essential nutrients and minerals. The loss of these nutrients inhibits normal body growth and may result in soft, bowed bones. Cysteine crystals also accumulate in the eyes, causing photophobia, an extreme sensitivity to light. Other symptoms may include muscle wasting, difficulty swallowing, diabetes, an underactive thyroid gland, and nervous system problems.
Less severe forms of the disease cause symptoms to begin later in life and may not affect the kidneys.
How common is Cystinosis?
Cystinosis affects approximately 1 in 200,000 people. The disease is most common in Brittany, France, where it affects 1 in 26,000.
How is Cystinosis treated?
Thanks to a drug called cysteamine, cystinosis has become easier to manage. Taken orally in capsules (brand name: Cystagon), it reduces the accumulation of cysteine crystals in the body. The drug has been shown to delay or prevent kidney failure and improve growth rates in children. Cysteamine eye drops have been successful in relieving photophobia in people with cystinosis, although they are not yet approved by the FDA for that purpose.
Nutritional monitoring is important in children with cystinosis. These children require a large amount of water to prevent dehydration. Supplements of several vitamins and minerals are also recommended for most people with the disease. Human growth hormone treatments have been shown to help people with cystinosis reach normal height.
Kidney transplants are an option for people with cystinosis. Cysteine crystals will not build up in the newly transplanted kidney, although they may still affect other organs of the body.
What is the prognosis for a person with Cystinosis?
Cystagon has extended the lifespan of people with cystinosis, but exact lifespan is not known. Some people with the disease have lived into their 50s.