Metachromatic leukodystrophy

[Becky]

Metachromatic leukodystrophy is a type of lysosomal storage disorder called a sphingolipidosis. It is caused by a buildup of fats (lipids) in the brain, spinal cord, kidneys, and spleen. This disease results in early death. Metachromatic leukodystrophy occurs when parents pass the defective genes that cause this disorder on to their children.

Metachromatic leukodystrophy occurs when the body lacks enzymes needed to break down a certain lipid.
Symptoms vary depending on whether the child has the infantile form or the juvenile form but may include paralysis, dementia, and nerve problems.
The diagnosis may be made by doing prenatal screening tests, nerve conduction studies, and blood and urine tests.
This disease causes premature death.
This disease cannot be treated or cured, but treatment options are being studied.

There are different types of inherited disorders. In metachromatic leukodystrophy, both parents of the affected child carry a copy of the abnormal gene. Because usually two copies of the abnormal gene are necessary for the disorder to occur, usually neither parent has the disorder. (See also Overview of Hereditary Metabolic Disorders.)
Sphingolipidoses occur when people do not have the enzymes needed to break down (metabolize) sphingolipids, which are compounds that protect the cell surface and serve certain functions in the cells. There are many types of sphingolipidoses besides metachromatic leukodystrophy:

Fabry disease
Gaucher disease (most common)
Krabbe disease
Niemann-Pick disease (types A and
Sandhoff disease
Tay-Sachs disease

In metachromatic leukodystrophy, an enzyme needed to break down a certain lipid, called arylsulfatase A, is not working correctly. This lipid builds up in the white matter of the brain and spinal cord, nerves, kidneys, spleen, and other organs. This buildup results in demyelination. Demyelination is the destruction of the tissue that wraps around nerves, called the myelin sheath. When the myelin sheath is damaged, nerves do not conduct electrical impulses normally. When impulses are not conducted normally, movements are jerky, uncoordinated, and awkward.