• hypoxic brain damage;
  • low birthweight;
  • perinatal complications;
  • monozygotic twin;
  • schizophrenia

Abstract A case is described herein of monozygotic twins discordant for schizophrenia that illustrates possible causal events of prenatal underdevelopment, morphological changes in the brain, poor premorbid functioning, and the development of schizophrenia. The affected twin was born with a birthweight of 1620 g, whereas the unaffected twin weighed 2300 g at birth. Marked differences in sociability and intelligence were observed between the twins from early childhood. Magnetic resonance imaging of the brain revealed high-intensity signals in the white matter and enlarged ventricles in the affected twin, while no such abnormality was detected in the well twin. This twin pair suggests a possibility that hypoxic brain damage associated with prenatal underdevelopment may be a causal factor for abnormalities in psychosocial development and subsequent schizophrenia.