Inherited Leukoencephalopathies

Leukoencephalopathies are disorders that selectively involve the white matter of the brain. Acquired causes of leukoencephalopathy include inflammatory, infectious, vascular, neoplastic, and toxic disorders. Hereditary leukoencephalopathies encompass conditions characterized by progressive destruction or loss of previously acquired central myelin (leukodystrophies) and conditions associated with impaired formation of myelin (dysmyelination or hypomyelination). The study of clinical features, neuroimaging patterns, and biochemical and neuropathologic features of leukoencephalopathies has led to the discovery of the genetic defects responsible for many of these conditions. Variations in phenotype-genotype correlation can make prediction of the underlying condition challenging. Despite recent advances in molecular studies, approximately 50% of patients with hereditary leukoencephalopathies remain without a diagnosis. A systematic approach to guide investigations is important for a diagnosis.