diffuse abnormal myelination
most common is late infantile presentation gait disorder and strabismus early in the 2nd year, speech impairment, spasticity, and retardation appear gradually, with steady progression

Cause - deficiency in the enzyme arylsulfatase A => myelin deficiency with accumulation of lipid sulfatide in macrophages and Schwann cells

IMAGING:
CT - low density white matter, progressive atrophy, no enhancement
MR - prolonged T1 and T2