Metachromatic leukodystrophy is a sphingolipidosis, an inherited disorder of metabolism, caused by arylsulfatase A deficiency, which causes progressive paralysis and dementia resulting in death by age 10 yr.
For more information, see Table Sphingolipidosis.
In metachromatic leukodystrophy, arylsulfatase A deficiency causes metachromatic lipids to accumulate in the white matter of the CNS, peripheral nerves, kidney, spleen, and other visceral organs; accumulation in the nervous system causes central and peripheral demyelination. Numerous mutations exist; patients vary in age at onset and speed of progression.
The infantile form is characterized by progressive paralysis and dementia usually beginning before age 4 yr and resulting in death about 5 yr after onset of symptoms.
The juvenile form manifests between 4 yr and 16 yr of age with gait disturbance, intellectual impairment, and findings of peripheral neuropathy. Contrary to the infantile form, deep tendon reflexes are usually brisk. There is also a milder adult form.
Diagnosis of metachromatic leukodystrophy is suggested clinically and by findings of decreased nerve conduction velocity; it is confirmed by detecting enzyme deficiency in WBCs or cultured skin fibroblasts. (Also see testing for suspected inherited disorders of metabolism.)
There is no effective treatment for metachromatic leukodystrophy.