Other disorders include a peculiar facial expression, mental retardation, movement disorders, microbrachycephaly, and various neurological disorders. Microcephaly, brachycephaly with occipital flattening are the main skull defects, usually in association with prognathism and midfacial retrusion.
Facial asymmetry occurs in some cases.
Deficient pigmentation of the choroid with optic pallor or atrophy and characteristic blue irides and Brushfield spots. Brisk tendon reflexes, hyperreflexia, hyperkinesia, hypsarrhythmia, epilepsy, and EEG abnormalities showing slow wave or spike activity are the principal neurological disorders. Pneumoencephalography indicates cerebral cortex atrophy and dilation of the cerebral ventricles. Hyperactivity, restlessness, jerky movements, ataxic gait or complete inability to walk and, absent speech, sleeping disorders, feeding problems, and drooling. Some cases are transmitted as an autosomal dominant trait but many are sporadic.