Molecular genetic etiology of twin reversed arterial perfusion sequence, , ,

OBJECTIVE: Our purpose was to determine whether the twin reversed arterial perfusion sequence (acardiac anomaly) results from fertilization of the first or second polar body. STUDY DESIGN: Placental or fetal tissue was obtained from nine twin sets discordant for twin reversed arterial perfusion. After deoxyribonucleic acid extraction, the polymerase chain reaction was used to amplify five polymorphic microsatellite repeats. The products were differentiated by polyacrylamide gel electrophoresis, and patterns were compared within twin sets. RESULTS: Deoxyribonucleic acid fingerprinting patterns were identical in all twin sets for all primer pairs. It is calculated that the chance that any of the acardiac twins resulted from fertilization of either the first or second polar body is <4% and the chance that they all resulted from polar body fertilization is <0.001%. CONCLUSIONS: Twins discordant for the twin reversed arterial perfusion sequence anomaly are monozygous. Our results exclude polar body fertilization as a likely cause of this condition. (AM J OBSTET GYNECOL 1996;174:891-4.)