Leukodystrophy
A disorder of the white matter of the brain, the part of the brain that contains myelinated nerve fibers.
The white matter is white because it is the color of myelin, the insulation covering the nerve fibers.
(The white matter is as opposed to the gray matter, the cortex of the brain which contains the nerve cell bodies).
The white matter is involved in the conduction of nerve impulses in the brain