[Preimplantation genetic diagnosis for beta-thalassemia].

Objective: To investigate the effect of in vitro fertilization and embryo transfer (IVF-ET) and preimplantation genetic diagnosis (PGD) for the couples at risk of having children with beta-thalassemia.
Methods: Four couples carrying different thalassemia mutations received standard IVF treatment. Embryo biopsy was conducted. Single blastomeres were genotyped by a protocol involving primer extension preamplification, nested polymerase chain reaction and reverse dot-blot analysis. Only the unaffected embryos were transferred to the uterus.
Results: A total of 97 oocytes were retrieved from the four female carriers. Among them, 83% showed two pronuclei. Embryo biopsy was performed on 47 of these embryos. The amplification efficiency was 84.8%. The average ADO rate was 14.9%. Ten unaffected embryos were transferred. A twin pregnancy with one blighted ovum was confirmed at 7 weeks' gestation by ultrasonography and one normal baby and one carrier of thalassemia mutation were born finally.
Conclusion: This unaffected pregnancy resulting from PGD for beta-thalassemia demonstrates that PGD technique can be a powerful diagnostic tool for couples carrying beta-thalassemia mutations who desire a healthy child and wish to avoid abortion of an affected fetus.