metachromatic leukodystrophy

metachromatic leukodystrophy n a hereditary neurological disorder of lipid metabolism characterized by the accumulation of cerebroside sulfates, loss of myelin in the central nervous system, and progressive deterioration of mental and motor activity

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an autosomal recessive disorder due to deficiency of cerebroside-sulfatase (caused by mutation in the ARSA gene, locus: 22q13.31-qter) or saposin B (caused by mutation in the PSAP gene, locus: 10q22.1). It is characterized by accumulation of sulfatide in neural and nonneural tissues, with a diffuse loss of myelin in the central nervous system. There are three forms due to deficiency of cerebroside sulfatase, with variable age of onset, all initially presenting as mental regression and motor disturbances. The infantile form usually begins in the second year of life and is additionally characterized by developmental delay, seizures, optic atrophy, ataxia, weakness, loss of speech, and progressive spastic quadriparesis. The juvenile form is clinically similar, but presents between the ages of 4 and 12 years and progresses more slowly; a variant of the juvenile form is caused by deficiency of saposin B. The adult form begins after 16 years of age, generally presenting initially as dementia and disturbances in behavior and progressing more slowly to motor and posture disturbances. Called also sulfatide lipidosis.