Girl-Boy Twins with Developmental Delay from 16p11.2 Triplication due to Biparental Inheritance from Two Parents with 16p11.2 Duplication.

The 16p11.2 duplication is a well-known cause of developmental delay and autism, but there are only 2 previously reported cases of 16p11.2 triplication.

Movement Disorders and Neurometabolic Diseases.

Many inherited metabolic diseases or inborn errors of metabolism (IEM) cause movement disorders in children. This review focuses on chorea, dystonia, myoclonus, tremor, and parkinsonism. Broad neurometabolic categories commonly responsible for pediatric movement disorders include mitochondrial cytopathies, organic acidemias, mineral metabolism and transport disorders, neurotransmitter diseases, purine metabolism abnormalities, lipid storage conditions, and creatine metabolism dysfunction.

Like father, like son: periventricular nodular heterotopia and nonverbal learning disorder.

Periventricular nodular heterotopia is a common malformation of cortical development in which the migration of developing neurons destined for the cerebral cortex is abbreviated. Bilateral periventricular nodular heterotopia is most commonly an X-linked disorder that involves mutations in the filamin A (FLNA) gene, but an autosomal recessive form and sporadic forms have been identified. To our knowledge, autosomal dominant transmission of isolated periventricular nodular heterotopia has not been reported.

A child with Friedreich's ataxia and epilepsy.

Epilepsy in Friedreich's ataxia is rare. We describe a 9-year-old boy with Friedreich's ataxia who had onset of symptoms in the second year of life and developed a generalized epilepsy at age 5 years. On cerebral magnetic resonance imaging, he has a subependymal gray-matter heterotopia.

Clinical findings in Pelizaeus-Merzbacher disease.

Pelizaeus-Merzbacher disease is a rare X-linked disease characterized by defective central nervous system myelination owing to a mutation in the proteolipid protein 1 gene. Few studies report detailed clinical findings in children with genetic confirmation of mutations in the proteolipid protein 1 gene. We reviewed the records of 10 boys with Pelizaeus-Merzbacher disease and one symptomatic carrier girl.