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Fabry Disease
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Description
Fabry disease is an inherited disease that affects anywhere from a few
thousand to 50,000 people worldwide. The most common form of Fabry
appears at twenty years of age. This disease is caused by a deficiency
of lysosomal enzyme a-galactosidase, which causes abnormal deposits of a
fatty substance called globotriaosylcera-mide in the blood vessels
throughout the body.
As abnormal storage of the fatty compound increases with time, the
channels of these vessels become narrowed. The narrowing leads to a
decreased blood flow and decreased nourishment of the tissues normally
supplied by those vessels. The problem occurs in all blood vessels
throughout the body, but affect in particular the skin, the kidneys, the
heart, the brain, and the nervous system. A characteristic rash around
the waist develops, and there is an increased risk of kidney and heart
disease as well as a reduced life expectancy.
Symptoms
In children it begins with episodes of pain and burning
sensations in hands and feet.
Young patients often develop spotted dark red skin rash seen more from
umbilicus to knees, decreased ability to perspire, change in cornea that
does not affect vision.
Fabry is a progressive disease. Symptoms of kidney, heart, and/or neuro
involvement occur between ages of 30-45.
Incidence and Carriers
The defective gene is on the X-chromosome. The X-chromosome is
one of two chromosomes that determine a person's sex. Females have two
X-chromosomes, one from each parent. Males have X-chromosome from mom
and Y-chromosome from dad.
If mother is a carrier of the Fabry Disease, all her male and female
children have 50% chance of inheriting a defective gene from their
mother.
If father is carrier all daughters will inherit the defective gene,
since it is the one X-chromosomes that is transferred from fathers to
daughters. Son, who get the Y-chromosome from their father do not
inherit the defective gene.
A female Fabry carrier has one X-chromosome with a defective gene and
normal one X-chromosome, thus she is usually protected. Males, on the
other hand, have only one X-chromosome, so when that gene is defective,
they express the disease.
Fabry Disease occurs in all ethnic groups. It is estimated that one in
200 people is a carrier, and one in 40,0000 has the disease.
Treatment
Treatment for Fabry disease is at first preventative. Certain factors
such as stress, exposure to sunlight, and change in temperature,
physical exertion, illness and fever trigger painful episodes. Patients
need to avoid these triggers to prevent the painful episodes.
Anticonvulsant medications such as Dilantin or Tegretol may be given for
reduce frequency of painful attacks.
Treatment is then geared toward any complications of the kidney. Mild
kidney dysfunction can be treated with diet, and those with severely
compromised kidney function are treated with dialysis and maybe
candidates for kidney transplant.
Testing
Once pregnant an Amniocentesis and a Chorionic Villus
Sampling can diagnose Fabry in the fetus before birth. Amniocentesis is
done between the 15th and 16th week of pregnancy. A needle is inserted
into the mother's abdomen and a sample of the fluid that surrounds the
baby is taken. In CVS a sample of cells from the placenta is retrieved
by the doctor during the 10th and 12th week of a pregnancy.
When Fabry disease is suspected either on basis of clinical signs or by
discovery of relative with Fabry disease it is confirmed by simple blood
test
that measures activity of enzyme.
Resources and More
International Center for Fabry Disease
Dept. of Human Genetics, Mount Sinai School of Medicine
5th Avenue and 100th Street
New York, NY 10029
Telephone: 212-659-6700
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