Leukodystrophy is one of a group of disorders characterized by degeneration of the white matter in the brain.[1] The word leukodystrophy comes from the Greek roots leuko, "white", dys, "lack of", and troph, "growth". The leukodystrophies are caused by imperfect growth or development of the myelin sheath, the fatty covering that acts as an insulator around nerve fibers.