Successful preimplantation genetic diagnosis of Hb Bart's hydrops fetalis in Singapore after fresh and frozen embryo replacement cycles

We report the fi rst successful preimplantation genetic diagnosis (PGD) for Hb Bart's hydrops fetalis in Singapore, involving both fresh and frozen embryo replacement cycles. Two couples who were carriers of the Southeast Asian type double gene deletion (--(SEA) deletion carriers) requested for PGD. Couple A had 2 previous affected pregnancies, while couple B have a child of unknown genotypic status. One PGD cycle was performed for each couple. The --(SEA) deletion was detected using a gap-PCR strategy. Couple A had 1 fresh-embryo replacement cycle while couple B underwent 2 frozen-embryo replacement cycles. Couple A achieved a twin pregnancy. Second trimester complications resulted in premature delivery, where 1 baby girl survived. Couple B achieved a singleton pregnancy resulting in delivery of a healthy baby boy. Genotype analysis of all babies confirmed the PGD results consistent with clinically unaffected status. We have successfully performed PGD to avoid Hb Bart's hydrops fetalis syndrome.