Mental retardation, ataxia, seizures, dysmorphia, and hydrocephaly in two sibs. Angelman syndrome or new syndrome.

We report two sibs with Angelman syndrome or an apparently new syndrome. In addition to severe mental retardation and seizures, clinical examination showed an ataxic and stiff legged gait, truncal hypotonia with hypertonia of the limbs, dysmorphic facial features (brachycephaly, large mouth, pointed chin and a prominent jaws) and scoliosis. Brain CT scan and MRI revealed ventricular enlargement and squared frontal horns. Pregnancy and delivery were uneventful. Karyotypes were normal. No deletion of chromosome 15q11-13 region was shown by molecular genetic techniques. The parents who are normal are second cousins. The condition is therefore probably inherited as an autosomal recessive one.