Twin sisters with psychotic disorders.

Abstract

These cases of twin sisters with psychotic illness were presented in a case conference to enhance the treatment of each twin by examining both cases together, to inform clinicians regarding issues relevant to the care of twins, and to evaluate the roles of genetics and environment in psychosis. Although the zygosity of these twins is open to question in the absence of blood group analysis or other genetic markers, several observations associated with monozygosity (1) are apparent in these cases. Specifically, childhood photographs show remarkable similarities in appearance of the twins, family members perceived them as identical, and examination of their placenta led the obstetrician to state they were most likely monozygotic. Today zygosity can be determined by a knowledgeably performed examination of the placenta and membranes at the time of birth in about two-thirds of cases (2).