About sulfatide lipidosis
What is sulfatide lipidosis?
Metachromatic leukodystrophy, the most common form of leukodystrophy, is a rare inherited neurometabolic disorder affecting the white matter of the brain (leukoencephalopathy). It is characterized by the accumulation of a fatty substance known as sulfatide (a sphingolipid) in the brain and other areas of the body (i.e., liver, gall bladder, kidneys, and/or spleen). The fatty protective covering on the nerve fibers (myelin) is lost from areas of the central nervous system (CNS) due to the buildup of sulfatide. Symptoms of metachromatic leukodystrophy may include convulsions, seizures, personality changes, spasticity, progressive dementia, motor disturbances progressing to paralysis, and/or visual impairment leading to blindness.
Metachromatic leukodystrophy is inherited as an autosomal recessive trait. There are three forms of the disease that have similar symptoms. However, they are distinguished by the age of onset: infantile, juvenile, and adult forms of metachromatic leukodystrophy.
What are the symptoms for sulfatide lipidosis?
General symptoms of MLD that are seen in all three forms of the disease include:
- abnormal muscle movement
- behavior problems
- decreased mental function
- decreased muscle tone
- difficulty walking
- difficulty eating or feeding
- frequent falls
- a loss of muscle control
- problems with nerve function
- difficulty speaking
- difficulty swallowing
What are the causes for sulfatide lipidosis?
Metachromatic leukodystrophy is an inherited disorder caused by an abnormal (mutated) gene. The condition is inherited in an autosomal recessive pattern. The abnormal recessive gene is located on one of the nonsex chromosomes (autosomes). To inherit an autosomal recessive disorder, both parents must be carriers, but they do not typically show signs of the condition. The affected child inherits two copies of the abnormal gene — one from each parent.
The most common cause of metachromatic leukodystrophy is a mutation in the ARSA gene. This mutation results in a lack of the enzyme that breaks down lipids called sulfatides that build up in the myelin.
Rarely, metachromatic leukodystrophy is caused by a deficiency in another kind of protein (activator protein) that breaks down sulfatides. This is caused by a mutation in the PSAP gene.
The buildup of sulfatides is toxic, destroying the myelin-producing cells ― also called white matter ― that protect the nerves. This results in damage to the function of nerve cells in the brain, spinal cord and peripheral nerves.
What are the treatments for sulfatide lipidosis?
There is no cure for MLD. Treatment for the condition focuses on managing your symptoms and improving your quality of life. Your doctor may use several different treatments to help manage your symptoms:
- medications to help control muscle movements and reduce pain
- therapy to improve speech, muscle movements, and quality of life
- nutritional assistance to cope with swallowing and eating difficulties
In some people, a bone marrow or cord blood transplant may be effective in slowing the progression of the disease. When successful, the healthy cells received in the transplant can make the ARSA that the body was missing. Though this procedure will not reverse damage already done by the disease, it can stop future damage to the nervous system and prevent mental disability for some people. This is most effective as an early intervention in people who show few or no symptoms.
As with any medical procedure, there are risks associated with bone marrow transplant. Risks associated with bone marrow transplant can be severe. The most common risks are graft-versus-host disease (GvHD) and rejection of the transplanted cells.
In some people, the newly transplanted cells recognize their cells as invaders and try to attack them. GvHD may cause:
- a fever
- a rash
- liver damage
- lung damage
The treatment for MLD includes drugs that suppress the immune system. The treatment will stop the attack but make you more likely to get an infection.
A bone marrow transplant usually involves suppressing the immune system to prevent rejection of the transplanted cells. This increases your chances of developing an infection. It’s important to treat any infection quickly to prevent it from developing into a more serious condition.
What are the risk factors for sulfatide lipidosis?
If the condition runs in your family, you may want to consider genetic testing and counseling to see if you’re a carrier. Genetic counseling may help you to be better informed about the risks of passing the gene on to your children.
Is there a cure/medications for sulfatide lipidosis?
MLD is a progressive disease. This means that the symptoms tend get worse over time. People who have this disease lose all muscle and mental function eventually. Lifespan often depends on the age at which a person is first diagnosed.
The disease progresses more quickly when it’s diagnosed at an early age. Children diagnosed with late infantile MLD typically live another five to 10 years. In juvenile MLD, the life expectancy is 10 to 20 years after diagnosis. If the symptoms don’t appear until adulthood, people typically live 20 to 30 years after the diagnosis.
Although there’s still no cure for MLD, more treatments are being developed. Talk to your doctor about participating in clinical studies.