Birth of healthy children after preimplantation diagnosis of beta-thalassemia.

Background: Clinical programs for preventing beta-thalassemia are presently based on prospective carrier screening and prenatal diagnosis. This paper report an achievement of a pregnancy with unaffected embryos using in vitro fertilization and embryo transfer (IVF-ET), in combination with preimplantation genetic diagnosis (PGD), for a couple at risk of having children with beta-thalassemia.

Methods: A couple carrying different thalassemia mutations, both a codon 41 - 42 mutation and the IVS II 654 mutation, received standard IVF treatment, with intracytoplasmic sperm injection, embryo biopsiy, single cell polymerase chain reaction (PCR) and DNA analysis. Only unaffected or carrier embryos were transferred to the uterine cavity. After confirmation of pregnancy, a prenatal diagnosis was performed.

Results: Of a total of 13 embryos analyzed for beta-globin mutations, PGD indicated that 2 were normal, 3 were affected, and 6 were carriers. Diagnosis could not be made in the other 2 embryos. Three embryos were transferred to the uterus on the third day after oocyte retrieval. Ultrasonography revealed a twin pregnancy with one blighted ovum. The prenatal genetic diagnosis revealed that both fetuses were unaffected, and two healthy boys were born, confirming the results of PGD.

Conclusions: We developed a single-cell based primer extension preamplification (PEP)-PCR assay for the detection of beta-thalassemia mutations. The assays were efficient and accurate at all stages of the procedure, and resulted in the birth of PGD-confirmed beta-thalassemia free children in China. PEP was used here in PGD for beta-thalassemia.