Expanding the Phenotype of Extremely Early Onset Juvenile Huntington's Disease: A Case Report and Review of Previously Published Cases.

Extremely early-onset juvenile Huntington's disease (HD) has been described in three patients with onset at approximately 18 months to 2 years of age. Herein, we report a patient with, to our knowledge, the youngest age of onset with the largest reported explicit expansion size. We also summarize the previously reported cases of extremely early-onset juvenile HD.

Evaluation of the Neonate with Seizures.

Neonatal seizures are common, occurring in 2 to 5 of 1,000 live births in the United States. The neonatal brain is thought to be predisposed toward seizures due to a combination of excessive excitatory and deficient inhibitory neuronal activity. The seizures tend to be focal or multifocal without secondary generalization, resulting in subtle seizure appearance.

Clinical Management of Dystonia in Childhood.

Dystonia is one of the most frequent movement disorders in childhood. It can impede normal motor development and cause significant motor disability. The diagnostic evaluation of childhood dystonia is challenging due to the phenotypic variability and heterogeneous etiologies.

Enhanced neuronal expression of major histocompatibility complex class I leads to aberrations in neurodevelopment and neurorepair.

Mice deficient in classical major histocompatibility complex class I (MHCI) have aberrations in neurodevelopment. The consequences of upregulated neuronal MHCI expression have not been examined. We found that transgenic C57Bl/6 mice that are engineered to express higher levels of self-D(b) on their CNS neurons have alterations in their hippocampal morphology and retinogeniculate projections, as well as impaired neurorepair responses.