Novel universal approach for preimplantation genetic diagnosis of β-thalassaemia in combination with HLA matching of embryos

Background: beta-Thalassaemia results from co-inheritance of two mutant beta-globin alleles. Allogeneic cord blood cell transplantation (CBT) from an HLA-identical sibling donor is an excellent treatment option for beta-thalassaemia. In families with an affected child and willing to have another child, IVF followed by preimplantation genetic diagnosis (PGD) can be applied to exclude affected embryos. Furthermore, healthy embryos could be HLA matched with the affected child so that cord blood from the future newborn can be used to transplant the affected sibling. Methods: We developed an indirect single-cell HLA typing technique based on the use of a bank of seven microsatellite markers within the HLA locus from which four informative and evenly distributed markers were selected. Results: The methodology was validated in three beta-thalassaemia families having six ovarian stimulation cycles in view of IVF and PGD. Six PGD cycles were performed in two families. On 58 embryos tested, the combined PCR was successful in 54 (93%). Two transfers were done and one clinical pregnancy was obtained. Using confirmatory analysis on 50 embryos, the accuracy for HLA typing was 100%. Conclusion: This strategy offers a new therapeutic option for patients with beta-thalassaemia and other monogenic diseases that can be cured with CBT.