MRI shows abnormal white matter maturation in classical holoprosencephaly.

In an attempt to assess white matter maturation in holoprosencephaly (HPE), MRI scans of 47 patients with HPE were retrospectively reviewed. White matter maturation was delayed in 25/47 patients, including 24/29 patients with classic HPE who were </=12 months old at the time of imaging. Of interest, all six patients with the middle interhemispheric (MIH) variant of HPE had normal myelination, regardless of age. This study provides further evidence that the classic and MIH variants of HPE have different underlying causes.