White matter changes associated with deletions of the long arm of chromosome 18 (18q- syndrome): a dysmyelinating disorder?

PURPOSE: To evaluate the MR findings in the central nervous systems of patients with deletions of the long arm of chromosome 18 (18q- syndrome).
METHODS: Sixteen patients with 18q- syndrome ranging in age from 3 to 46 years (mean, 17 years) were studied with high-field-strength MR imaging. Images were analyzed for abnormal T2 hyperintensity in the white matter, abnormal T2 hypointensity in the deep gray matter, and atrophy.
RESULTS: Ten of 16 patients had abnormal white matter. Diffuse, bilaterally symmetric deep white matter T2 hyperintensity, most pronounced in the periventricular regions, was most common, noted in eight cases. Focal deep white matter lesions and/or abnormalities involving the subcortical white matter were also noted in four cases. The cerebellum, brain stem, and corpus callosum were spared. Ventriculomegally associated with volume loss, and abnormal T2 hypointensity in the basal ganglia and/or thalami were each present in 11 patients.
CONCLUSIONS: The 18q- syndrome is associated with white matter disease and abnormal T2 hypointensity in the deep gray matter. The basis for the white matter abnormalities is unknown, but may be related to one of the two genes for myelin basic protein included in the deleted segment of chromosome 18.