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.