= MLD = most common hereditary (autosomal recessive) leukodystrophy (dysmyelinating disorder)

Cause: deficiency of arylsulfatase A resulting in severe deficiency of myelin lipid sulfatide within macrophages + Schwann cells

Age of presentation: before age 3 (⅔), in adolescence (⅓)

1. LATE INFANTILE FORM
   Age: 2^nd year of life
   • gait disorder + strabismus, impairment of speech
   • spasticity + tremor, intellectual deterioration
   
   Prognosis: death within 4 years of onset
2. JUVENILE FORM
   Age: 5–7 years
3. ADULT FORM
   • organic mental syndrome
   • progressive corticospinal, corticobulbar, cerebellar, extrapyramidal signs

• progressive loss of hemispheric brain tissue

CT:

• symmetric low density of white matter adjacent to ventricles (esp. centrum ovale and frontal horns)
• progressive atrophy
• no contrast enhancement

MR:

• progressive symmetrical areas of hypointensity on T1WI
• hyperintensity on T2WI (increased water)
• early sparing of internal capsule + subcortical U-fibers

Prognosis: death within several years