(From the Brochure)
- WHAT IS CYSTINOSIS?
- Cystinosis is a metabolic disease characterized by an abnormal
accumulation of the amino acid cystine in various organs of the body such as
the kidney, eye, muscle, pancreas, and brain. Different organs are affected at
- IS IT INHERITED?
- The disease is inherited in an autosomal recessive fashion,
meaning that each parent of a child with cystinosis carries one defective gene
and one normal gene. The parents never have any signs of the disease.
- WHAT CAUSES CYSTINOSIS?
- The cystine content of cystinotic cells averages 50-100 times the
normal value. The cause is a defect in the transport of cystine out of a cell
compartment called the lysososme, in which cystine accumulates. Because of
cystine's low solubility, this amino acid forms crystals within the lysosomes
of cells, and this is probably what destroys the cells.
- WHAT ARE THE SYMPTOMS?
- There are three clinical forms of cystinosis. Infantile (or
nephropathic) cystinosis; late-onset cystinosis; and benign cystinosis. The
latter form does not produce kidney damage. Infantile and late-onset cystinosis
differ in the age of appearance of the first symptoms and in the rapidity of
the clinical course. Infantile cystinosis is usually diagnosed between 6 and 18
months of age with symptoms of excessive thirst and urination, failure to
thrive, rickets, and episodes of dehydration. These findings are caused by a
disorder called renal tubular reabsorb nutrients and minerals. As a
consequence, these important molecules are lost in the urine. Children with
cystinosis also have crystals in their eyes (after one year of age) and an
increased level of cystine in their white blood cells. Without specific
treatment, children with cystinosis develop end-stage renal failure, i.e., lose
their kidney function, at approximately 9 years of age.
- If cystinosis patients receive a kidney transplant and reach
adulthood, their new kidney will not be affected by the disease. However,
without cysteamine treatment (see below), they can develop complications in
other organs due to the continued accumulation of cystine throughout the body.
These complications can include muscle wasting, difficulty swallowing,
diabetes, heypthroidism, and blindness. Not all older patients develop these
- CAN CYSTINOSIS BE TREATED?
- The symptomatic treatment of the Fanconi syndrome
is essential. The urinary losses of water, salts, bicarbonate, and minerals
must be replaced. Most children receive a solution of sodium and potassium
citrate, as well as phosphate. Some also receive extra vitamin D.
- The aim of specific treatment for cystinosis is to
reduce cystine accumulation within the cells. This goal is achieved by
cysteamine treatment, which has proven effective in delaying or preventing
renal failure. Cysteamine also improves growth of cystinosis children. The Food
and Drug Administration (FDA) has approved a capsule form of cysteamine called
CYSTAGON . .
- Kidney transplantation has proven very helpful in patients with
cystinosis, and cysteamine therapy should be considered to try to prevent the
late complications of the disease (see above)..
- For both young children with cystinosis and older patients with a
kidney transplant, cysteamine eyedrops may be available to remove the corneal
cystine crystals. However, these are not yet approved by the FDA.
- IS PRENATAL DETECTION POSSIBLE?
- Today, prenatal diagnosis is available for families known to be at
risk for having a child with cystinosis. Chorionic villus sampling is performed
at 8-9 weeks of gestation; amniocentesis can be performed at 14-16 weeks of