Update on genetic disorders affecting white matter

The classification of diseases affecting white matter has changed dramatica lly with the use of magnetic resonance imaging. Classical leukodystrophies, such as metachromatic leukodystrophy and Krabbe's disease, account for onl y a small number of inherited diseases that affect white matter. Magnetic r esonance imaging has clarified genetic disorders that result in white matte r changes or leukoencephalopathies. The term leukoencephalopathy is used to reflect the broader number of diseases that may cause as either primary or secondary changes in myelin development. This review attempts to categoriz e white matter disorders into classes such as lipid, myelin protein, organi c acids, and defects in energy metabolism, in addition to other causes, (C) 2001 by Elsevier Science Inc. All rights reserved.