Twin anemia-polycythemia sequence with blood chimerism in monochorionic dizygotic opposite-sex twins.

We report a case of twin anemia-polycythemia sequence with blood chimerism in monochorionic dizygotic twins born to a 30-year-old woman who conceived via ovulation induction. The neonates developed twin anemia-polycythemia sequence; the female twin had anemia and the male had polycythemia. We detected blood chimerism using fluorescence in situ hybridization (FISH). Twin anemia-polycythemia sequence carries not only perinatal risks, but also genetic and immunological implications due to blood chimerism. Although previous reports have described twin-to-twin transfusion syndrome in monochorionic dizygotic twins, we report the first case of twin anemia-polycythemia sequence in monochorionic dizygotic twins.