Patchy white matter hyperintensity in ring chromosome 18 syndrome.

Ring chromosome 18 syndrome is a chromosomal abnormality in which partial deletions occur at both ends of chromosome 18, that is, distally on the short and long arms. Previously reported brain magnetic resonance imaging (MRI) abnormalities include diffuse hyperintensity in the white matter, which has been regarded as hypomyelination because the gene for myelin basic protein production is located on the long arm of chromosome 18. We report the case of a 14-year-old boy with ring chromosome 18 syndrome, whose MRI showed patchy asymmetrical T2 and fluid-attenuated inversion-recovery hyperintensities in the deep white matter as well as diffuse hypomyelination. These patchy lesions may indicate demyelination or gliosis rather than hypomyelination. This result differs from previous reports.