About Cystinosis

Cystinosis is a rare, inherited, metabolic disease that is characterized by the abnormal accumulation of the amino acid cystine in each cell. The build-up of cystine in the cells slowly and eventually destroys all major organs of the body including the kidneys, liver, eyes, muscles, bone marrow, thyroid and brain. Although medication is available to control some of the symptoms of this insidious disease, cystinosis remains incurable.

Cystinosis is known as an orphan disease. An "orphan disease" is defined as a disease that affects less than 200,000 people. Research money for rare diseases is scarce yet there are over 6,000 rare diseases in the United States affecting over 25 million Americans.

Watch the Cystinosis Research Foundation informational video

Symptoms:
There are three clinical forms of cystinosis. Infantile (nephropathic) cystinosis; late-onset cystinosis; and benign cystinosis. Infantile cystinosis is the most severe and the most common type of cystinosis. Children with nephropathic cystinosis appear normal at birth but by 9-10 months of age, have symptoms that include excessive thirst and urination and failure to thrive. Children often appear pale and thin and have short stature. The abnormally high loss of phosphorous in the urine leads to rickets.

After one year of age, cystine crystals appear in the cornea and cause a severe sensitivity to light (photophobia). Children with cystinosis also have an increased level of cystine in their white blood cells. In time, patients can develop problems such as hypothyroidism, severe muscle weakness and central nervous system complications. These children have normal intelligence, but have an unusual defect in short-term visual memory. Many have poor GI motility. Cystagon TM causes hyper secretion of gastric acid, resulting in gastric distress.

Treatment:
Fanconi Syndrome is treated symptomatically. Fanconi Syndrome causes a loss of minerals and nutrients in the urine. Treatment requires free access to water and oral replacement of salts and minerals that are lost in the urine. High doses of vitamin D and phosphate are required to replace the lost nutrients and minerals and to prevent rickets.

The only specific treatment for cystinosis is cysteamine. Cysteamine is the only drug that slows the progression of cystinosis by removing the cystine from the cells. Cysteamine is a cystine depleting agent that helps to lower cystine levels in the cells. Cysteamine was designated an "orphan drug" as defined under the Orphan Drug Act of 1983. In 1992, Mylan Laboratories assumed responsibility for developing cysteamine in a capsule form. In 1994, the new product, called CystagonTM was available for use. Unfortunately CystagonTM has a very bad taste and smell and must be taken every six hours, every day.

Cysteamine eye drops help to dissolve cystine crystals on the cornea. In patients with severe photophobia, using these drops every hour while awake can remove the cystine crystals from the cornea. A pharmaceutical company is proposing these drops for FDA approval.

Although renal transplantation is usually required in patients with cystinosis who are diagnosed late and do not begin CystagonTM treatment at an early age, even patients who start CystagonTM at an early age may eventually require transplantation. This may be because patients find it impossible to continue taking CystagonTM four times a day at six hour intervals for their entire lives.

Effects of Cystinosis
Over a period of years, the cystine damages various organs including the kidneys, liver, muscles, white blood cells, eyes and central nervous system. The cystine crystallizes in cells throughout the body, slowly destroying the organs. The earliest abnormalities are seen in the kidney. Cystinosis is a common cause of the Fanconi syndrome, a renal tubular disease. by about one year of age, patients have very large volumes of urine and lose large amounts of salt and other minerals in their urine.

Without specific treatment, these children progress to end-stage renal failure by an average age of nine years. In the past, this meant death. Now these patients can receive renal dialysis or renal transplantation. However, even with successful renal transplantation, these children go on to develop abnormalities in other organs.

Fortunately, the drug cysteamine slows the progression of cystinosis by removing the cystine from the cells. In order for the drug treatment to be effective, it must be taken every six hours. Although this has led to a much better future for these children, cysteamine is not a cure.

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