Abnormal cerebral cortical neurons in a child with maternal PKU syndrome.

A child born to a phenylketonuric (PKU) woman not on dietary treatment was microcephalic and had congenital heart and other physical anomalies consistent with the maternal PKU syndrome. After a repeat cardiac catherization at 3 months of age, he suffered an embolic left cerebral infarct and seizures. He was found by his mother dead in bed at 4 months of age; general autopsy revealed Klebsiella sepsis and pneumonia. Neuropathologic studies of the right cerebral hemisphere showed neuronal loss of the third cortical layer; Golgi studies revealed persistently immature cortical pyramidal cell somata and dendritic spines. This is the first report of specific neuronal abnormalities in a child with the maternal PKU syndrome and may, in part, account for the clinical features of microcephaly, mental retardation, and seizures seen in affected children.