Confined Blood Chimerism in Monochorionic Diamniotic Dizygotic Twin

Abstract

Monochorionic diamniotic dizygotic (MCDADZ) twins are extremely rare. However, MCDADZ cases have been reported as in vitro fertilization-embryotransfer has become more common and genetic tests have become possible. In MCDADZ twin, vascular anastomosis occurs by sharing the placenta, then twin-twin transfusion syndrome or the confusion in blood typing or genetic test due to blood chimerism can occur. Authors report a case of MCDADZ twin who showed blood chimerism detected by karyotyping and chromosome microarray. They were born through in vitro fertilization, and confined blood chimerism was diagnosed by additional short tandem repeat study. Although there was no twin-twin transfusion syndrome or disconcordant blood-typing in our twins, genetic counseling and long-term follow up is needed for possible confusion in laboratory test due to persistent blood chimerism in the future.