Motor, sensory, and integrative activities of the brain are coordinated by a series of midline-bridging neuronal commissures whose development is tightly regulated. Here we report a novel human syndrome in which these commissures are widely disrupted, causing clinical manifestations of horizontal gaze palsy, scoliosis, and intellectual disability. Affected individuals were found to possess biallelic loss-of-function mutations in the axon guidance receptor Deleted in Colorectal Carcinoma (DCC), a gene previously implicated in congenital mirror movements when mutated in the heterozygous state, but whose biallelic loss-of-function human phenotype has not been reported. Structural MRI and diffusion tractography demonstrated broad disorganization of white matter tracts throughout the human CNS including loss of all commissural tracts at multiple levels of the neuraxis. Combined with data from animal models, these findings show that DCC is a master regulator of midline crossing and development of white matter projections throughout the human CNS.
Results from comprehensive neuropsychological assessments of children diagnosed with epilepsy have rarely been reported. Previous research has generally focused on the measurement of overall intellectual ability and achievement skills. In the present study, neuropsychological evaluations including memory, attention, language, achievement, fine motor, executive function, visual motor integration, and behavior were completed on children (n = 79) diagnosed with epilepsy. Neurocognitive skills were within expectations for measured intelligence with the exception of verbal and visual attention skills, which were significantly below expectations based on measured ability. Behaviorally, children were rated by their parents as demonstrating clinically elevated attentional problems. Differences in cognitive and behavioral function were not found according to seizure type. Findings suggested a more diffuse effect of childhood epilepsy reflected in a pattern of decreased attention skills.
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