Biallelic mutations in human DCC cause developmental split-brain syndrome.

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 new human syndrome in which these commissures are widely disrupted, thus causing clinical manifestations of horizontal gaze palsy, scoliosis, and intellectual disability. Affected individuals were found to possess biallelic loss-of-function mutations in the gene encoding the axon-guidance receptor 'deleted in colorectal carcinoma' (DCC), which has been implicated in congenital mirror movements when it is 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 central nervous system (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.

Pontine tegmental cap dysplasia with a 2q13 microdeletion involving the NPHP1 gene: insights into malformations of the mid-hindbrain.

The case of a young man with multiple brain and somatic anomalies that presented diagnostic difficulties, is discussed in this report. A majority of his features were suggestive of Joubert syndrome--although it was felt that he did not fully meet diagnostic criteria. The subsequent evaluations included a magnetic resonance image of the brain, that was found to be consistent with pontine tegmental cap dysplasia. Chromosomal microarray studies showed a 2q13 deletion. A gene associated with Joubert syndrome, NPHP1, is within this region. This case highlights several important aspects of the diagnosis and nosology of malformations of the mid-hind brain.

Functional MRI and Wada determination of language lateralization: a case of crossed dominance.

The Wada test has historically been the conventional procedure for determining language lateralization before neurosurgery. However, functional magnetic resonance imaging (fMRI) offers a less invasive alternative to the Wada procedure. Research indicates that the two techniques used together may provide comparable, and sometimes complementary, information that results in improved prediction of postsurgical language ability. We present a case in which use of fMRI in conjunction with Wada testing provided complementary information about language lateralization before neurosurgical resection of a mesial temporal subependymoma for seizure control in a patient with schizencephaly.

Screening for autoantibodies in children with opsoclonus-myoclonus-ataxia.

Various paraneoplastic autoantibodies have been linked to discrete neurologic syndromes and tumors in adults, but little is known about their incidence in children. We report a cross-sectional study of known paraneoplastic antibodies in 59 children with opsoclonus-myoclonus-ataxia, 86% of whom were moderately or severely symptomatic, and 68% of whom had relapsed at the time of testing. This total number of patients includes 18 children with low-stage neuroblastoma (tested after tumor resection), six of whom had never been treated with immunosuppressants. All were seronegative for anti-Hu, anti-Ri, and anti-Yo, the three paraneoplastic antibodies most associated with opsoclonus-myoclonus or ataxia in adults. These data contrast with reports of anti-Hu-positive sera in children with high-stage tumors and suggest that anti-Hu, anti-Ri, and anti-Yo do not explain relapses in pediatric opsoclonus-myoclonus-ataxia. They underscore the need to search for unique autoantibodies, as well as cellular mechanisms of pediatric paraneoplastic disease.