Metachromatic Leukodystrophy
Alternate Names : Arylsulfatase A Deficiency, MLD
Definition
Metachromatic leukodystrophy is an inherited disease characterized by the absence of the enzyme arylsulfatase A, which causes a material called cerebroside sulfate to accumulate in cells. This is toxic to the cell, especially neurons (the cells of the nervous system) and causes the problems of the disease.
MLD is a member of a class of diseases called lysosomal storage disorders. In these diseases, patients lack a protein needed to metabolize the food we eat.
Overview, Causes, & Risk Factors
Metachromatic leukodystrophy (MLD) is transmitted as an autosomal recessive trait, which means that a person must inherit the defective gene from both parents to be affected.
MLD has a wide range of symptoms. As with many other storage diseases, there are forms of early and delayed onset (late infant, juvenile, and adult types).
The most common and most severe form is the late infant onset form, which has symptoms such as irritability, decreased muscle tone, muscle wasting, and the loss of the ability to walk in babies who have started walking. The disease progresses to blindness, seizures, and partial paralysis. Death occurs usually before age 10.
Both the juvenile and adult forms have similar symptoms. In the adult and juvenile forms, psychosis and emotional disturbances are often part of the illness. Patients can be misdiagnosed with a psychiatric disorder before the diagnosis of MLD is made. The juvenile form is fatal within a few years of diagnosis. The adult form may be drawn out over many years.
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