First unaffected pregnancy using preimplantation genetic diagnosis for sickle cell anemia.
Overview
abstract
CONTEXT: Sickle cell anemia is a common autosomal recessive disorder. However, preimplantation genetic diagnosis (PGD) for this severe genetic disorder previously has not been successful. OBJECTIVE: To achieve pregnancy with an unaffected embryo using in vitro fertilization (IVF) and PGD. 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 genetic 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, embryo biopsy, single-cell polymerase chain reaction and DNA analyses, embryo transfer to uterus, pregnancy confirmation, and prenatal diagnosis by amniocentesis 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 carrier embryos to be transferred. RESULTS: The first IVF attempt failed to produce a pregnancy. Of the 7 embryos analyzed in the second attempt, PGD indicated that 4 were normal and 2 were carriers; diagnosis was not possible in 1. Three embryos were transferred to the uterus on the fourth day after oocyte retrieval. A twin pregnancy was confirmed by ultrasonography, and subsequent amniocentesis revealed that both fetuses were unaffected and were not carriers of the sickle cell mutation. The patient delivered healthy twins at 39 weeks' gestation. CONCLUSION: This first unaffected pregnancy resulting from PGD for sickle cell anemia demonstrates that the technique can be a powerful diagnostic tool for carrier couples who desire a healthy child but wish to avoid the difficult decision of whether to abort an affected fetus.
