Different molecular mechanisms leading to white matter hypomyelination in infantile onset lysosomal disorders.

Hypomyelinating leukoencephalopathies may be related to a primary disturbance in the formation of myelin or may be caused by neuronal, oligodendrocytic or astrocytic dysfunction, leading to a failure of myelination. Abnormal myelination related to a direct metabolic damage on oligodendrocytes has been shown to occur in some animal models of lysosomal storage diseases. To demonstrate that cerebral white matter hypomyelination may occur also in humans affected by early-onset lysosomal storage diseases, we report three cases with infantile-onset lysosomal storage disorders (type 1 GM1 gangliosidosis, globoid cell leukodystrophy or Krabbe's disease, and type A Niemann-Pick disease) showing white matter hypomyelination. Hypomyelinating leukoencephalopathy may therefore represent a feature of lysosomal storage disorders with onset in the first months of life, when the process of myelination is particularly active, indicating that neuronal storage disorders may be primarily responsible for central nervous system hypomyelination.