First unaffected pregnancy using preimplantation genetic diagnosis for sickle cell anemia

Context Sickle cell anemia is a common autosomal recessive disorder. Howeve r, pre implantation genetic diagnosis (PCD) for this severe genetic disorde r previously has not been successful. Objective To achieve pregnancy with an unaffected embryo using in vitro fer tilization (IVF) and PCD, Design Laboratory analysis of DNA from single cells obtained by biopsy from embryos in 2 IVF attempts, 1 in 1996 and 1 in 1997, to determine the genet ic status of each embryo before intrauterine transfer. Setting University hospital in a large metropolitan area. Patients A couple, both carriers of the recessive mutation for sickle cell disease. Interventions Standard IVF treatment, intracytoplasmic sperm injection, emb ryo biopsy, single-cell polymerase chain reaction and DNA analyses, embryo transfer to uterus, pregnancy confirmation, and prenatal diagnosis by amnio centesis at 16.5 weeks' gestation, Main Outcome Measure DNA analysis of single blastomeres indicating whether embryos carried the sickle cell mutation, allowing only unaffected or carri er embryos to be transferred. Results The first IVF attempt failed to produce a pregnancy. Of the 7 embry os analyzed in the second attempt, PCD indicated that 4 were normal and 2 w ere carriers; diagnosis was not possible in 1. Three embryos were transferr ed to the uterus on the fourth day after oocyte retrieval. A twin pregnancy was confirmed by ultrasonography, and subsequent amniocentesis revealed th at both fetuses were unaffected and were not carriers of the sickle cell mu tation. The patient delivered healthy twins at 39 weeks' gestation. Conclusion This first unaffected pregnancy resulting from PGD for sickle ce ll anemia demonstrates that the technique can be a powerful diagnostic tool for carrier couples who desire a healthy child but wish to avoid the diffi cult decision of whether to abort an affected fetus.