Aicardi syndrome in one dizygotic twin.

The Aicardi syndrome consists of infantile spasms, defects of the corpus callosum, dorsal vertebral anomalies, and chorioretinal lacunar defects. The etiology is, as yet, unknown. The most likely cause, however, is an X-linked mutational event that is lethal in males. The first case of the Aicardi syndrome known to occur in one twin is reported. The patient was female and her unaffected sibling was male. This provides strong evidence to support the theory of an X-linked mutational event as the cause of this condition. The typical chorioretinal defects, often difficult to document because these children die at an early age, are clearly illustrated in this report.