What is Fabry Disease?
Fabry disease is an uncommon X-linked recessive trait that involves lysosomal storage disease that causes varied symptoms involving different systems in the body. It is also known as Anderson-Fabry disease, Fabry’s disease, alpha-galactosidase A deficiency, or angiokeratoma corporis diffusum.
Fabry disease is characterized by a lack of enzymes required for metabolism of lipids. This enzyme is known as ceramide trihexosidase enzyme or alpha-galactosidase A enzyme. Lipids generally come from fats, waxes, oils and fatty acids from foods.
The cause of Fabry’s disease is a mutation in the gene responsible for the regulation of the enzyme. Consequentially, there is insufficient metabolism of lipids, leading to build-up of harmful lipids in organs such as the kidneys, eyes, nervous system, and cardiovascular system. Fabry disease is considered a very rare disorder which leads to a lack of complete understanding by some physicians and misdiagnosis.
Symptoms of Fabry Disease
Symptoms usually occur early in childhood and they appear to be bizarre. The symptoms also worsen as the child grows because of the increased intake of fats. Symptoms include:
Acroparesthesia is the occurrence of localized pain in the extremities, whole body, or in the gastrointestinal tract as a result of damage to the peripheral nerve fibers. These nerve fibers are responsible for the transmission of pain. Pain in the gastrointestinal tract may also be caused by accumulation of lipids in small blood vessels in the gastrointestinal tract, leading to obstruction of blood flow to the cells and pain. Pain in the extremities is usually aggravated by hot weather and exercise.
- Cardiac Symptoms
The cardiovascular system also suffers from accumulation of lipids, leading to hypertension and cardiomyopathy. Symptoms of cardiac affectation may include high blood pressure, palpitations, chest pain, and cyanosis of the extremities as a result of obstruction of peripheral blood flow by the lipids. In the long run, Fabry disease may lead to cardiovascular diseases such as Reynaud’s disease, coronary artery disease, myocardial infarction, or stroke.
- Renal Symptoms
The kidneys are also affected and can result in renal failure. Manifestations include proteinuria or the presence of protein in the urine, oliguria or scanty urination, and flank pain. End stage renal disease is usually experienced by males in their thirties.
- Skin manifestations
The skin may also develop lesions as a sign of the condition. Angiokeratomas are painless and tiny papules that may grow on all parts of the body, especially on the groin, belly button, buttocks, thighs and lower abdomen. Anhidrosis is another manifestation involving a lack of sweating.
- Eye symptoms
The eyes are especially involved in the progression of the disease because any obstruction in the small blood vessels may cause significant symptoms. One symptom is the presence of clouding of the corneas or cornea verticillata or vortex keratopathy. This is a classical feature of asymptomatic carriers of the gene. However, clouding of the cornea may not affect the vision of the patient. Other eye problems include optic atrophy, macular edema, papilledema, cataracts and conjunctival aneurysms.
- Other symptoms
Other organ affectations may lead to nausea, vertigo, difficulty in weight gaining, tinnitus or ringing of the ears, and diarrhea because of the inability to metabolize and use lipids.
Inheritance & prevalence
The presence of a deficiency in the alpha-galactosidase A enzyme is a result of gene mutation. In this regard, it is considered an X-linked recessive trait. It affects hemizygous and homozygous males as well as heterozygous females. Males usually develop more severe symptoms than females; however, females may also experience symptoms ranging from asymptomatic to severe. X-linked, the DNA mutation is carried by the mother in her X-chromosome. Affected mothers have the chance to transmit it to their offspring. Sons have a 50% chance to develop the disease while daughters have a 50% chance to be a carrier of the trait.
More men are affected than women with a prevalence of one in every 40,000 males and one in every 120,000 people. The disease is more common in Caucasians, but may also be seen in Hispanics, African American and Asians. There is up to a 1.2% prevalence of Fabry disease in the world.
Diagnosis of Fabry Disease
The diagnosis of Fabry disease is initiated through physical assessment and a review of symptoms. Specific tests are done to ascertain the diagnosis, including:
- Blood test
A blood test is done to determine the level of alpha-galactosidase.
- Chromosomal Analysis
This is the most accurate diagnostic procedure for Fabry disease, chromosomal analysis looks at the GLA gene for any mutations.
- Kidney Biopsy
Affectation of the kidneys may prompt a kidney biopsy to determine significant changes in the morphologic structures of the nephrons.
Treatment for Fabry Disease
Previous treatments for Fabry disease only involved symptomatic relief of patients. However, because of advancement in treatments, specific treatments are available to correct the lack of alpha-galactosidase A enzyme. Treatments include:
Enzyme Replacement Therapy (ERT)
This treatment involves the administration of exogenous enzymes that help metabolize lipids. These include Agalsidase beta or Fabrazyme and Agalsidase alpha or Replagal. This therapy involves replacing the deficient enzyme with these drugs once every two weeks. The drug is administered via infusion. Enzyme replacement therapy is quite expensive, requiring up to $250,000 a year. Because of this, treatment with ERTs is generally inaccessible by a lot of people. The administration of the medicine can be done in a medical facility or at home with a nurse. Enzyme replacement therapy cannot cure the problem but provides the body with the needed enzyme in order to metabolize lipids. This treatment is specifically given to prevent progression of the disease as well as reverse the symptoms.
Pain relievers are also given to reduce pain. These include anti-inflammatory drugs, analgesics or anticonvulsants. Anticonvulsants are given even if there are no seizures because these drugs stabilize the nerve impulse transmission from the peripheral nerve fibers.
People with Fabry disease generally have a reduced life expectancy because of systemic affectations. Patients usually die of heart diseases, kidney failure, and recurrent stroke. Deaths related to complications of Fabry disease happen between age forty and sixty.