Hippocampal abnormalities in magnetic resonance imaging (MRI) of 15q duplication syndromes.

Patients with 15q duplication syndromes, including isodicentric chromosome 15 and interstitial duplications, usually present with autism spectrum disorder, intellectual disability, and frequently epilepsy. Neuroimaging studies in these patients are typically reported as normal, but nonspecific findings such as thinning of the corpus callosum and increased pericerebral spaces have been reported. A review of brain magnetic resonance imaging (MRI) studies of 11 individuals seen at the Massachusetts General Hospital Dup15q Center was performed. Hippocampus morphology was specifically reviewed, as a recent neuropathologic study has found frequent hippocampal heterotopias and dysplasias in these disorders. Two subjects had unilateral hippocampal sclerosis and 6 had bilateral hippocampal malformations. Hypoplasia of the corpus callosum was present in 2 subjects.