Haematopoietic stem cell transplantation (HSCT) remains the best therapeutic option for many acquired and inherited paediatric haematological disorders. Unfortunately, the probability of finding an HLA matched donor is limited. An alternative technique is PGD combined with HLA matching, which offers the possibility of selecting unaffected embryos that are HLA compatible with the sick child, with the aim of possible use of stem cells from the resulting baby in future. Since the first successful report for Fanconi anaemia a decade ago, the therapeutic success of this technique was reported in a few cases and for a limited number of disorders. Here, we report full recovery of 44 sick children who received HSCT from healthy infants conceived after pre-implantation HLA matching for the following 10 indications; beta-thalassaemia, Wiskott-Aldrich syndrome, Fanconi anaemia, sickle cell anaemia, acute myeloid leukaemia, acute lymphoblastic leukaemia, Glanzmann's thrombasthaenia, Diamond-Blackfan anaemia, X-linked adrenoleukodystrophy and mucopolysaccharidosis type I. No serious complications were observed among recipients and donors. Graft failure occurred in four children with beta-thalassaemia where a second HSCT was planned. Preimplantation HLA matching is a reliable technique and provides a realistic option for couples seeking treatment for an affected child when no HLA-matched donor is available.
Preimplantation Genetic Diagnosis (PGD) is currently an alternative for couples with high risk of pregnancies with genetic anomalies; it offers the possibility of avoiding the need to terminate affected pregnancies, since it allows the selection of unaffected embryos for transfer. PGD for inherited disorders has become extremely accurate (99.5%), and may currently be performed for any single gene disorders in which mutation is identified. PGD has been performed for more than 100 different conditions resulting in the birth of at least 1000 healthy children free of genetic disorder. PGD is presently also used together with preimplantation HLA typing for treatment of affected sibling with genetic and acquired disorders requiring HLA matched stem cell transplantation. This is not only to allow couples to have an unaffected child but also to select a potential donor progeny for stem cell transplantation. In Turkey, thalassemia is the most commonly seen genetic disorder the rate of thalassemia carriers is about 3 -4% in Turkey. The majority of our PGD cases are thalassemia carriers. They do not only require thalassemia mutation analysis but also HLA typing for their affected child. In this study PGD results of 236 Turkish couples with or without HLA typing will be presented and discussed. A full diagnosis was achieved in 91.0% of the biopsied samples. In Group I, 17.8% of the analyzed embryos were found to be HLA compatible. HLA compatible and disease free embryos were 12.9% of all diagnosed embryos. In group II, 17.2% of embryos were found to be HLA matched and 71.4% HLA non-matched. The majority of our HLA typing combined with PGD cases were β-Thalassemia carriers (87.9%). The mutations analyzed have high heterogeneity, the most frequent mutation was IVS-I-110 G-A and comprised 46.2% of all mutations. To date, 70 healthy and HLA compatible children have been born. Twenty-five sick children have already been cured with cord blood cell and/or bone marrow transplantation. Twenty-one children are waiting for their newborn siblings to gain sufficient weight and maturity for the donation of stem cells. The successful transplantations have been performed for the following indications: β-Thalassemia (n=19), Wiskott Aldrich syndrome (n=2), Glanzmann Disease (n=1), X-Adrenoleukodystrophy (n=1) and acute myeloid leukemia (n=1) and Diamond Blackfan anemia (n=1). This data presents one of the world's largest experiences on preimplantation HLA typing, and the outcome of stem cell transplantation is the largest number available from one center. Our results indicate HLA typing with or without mutation analysis is a promising and effective therapeutic tool for curation of an affected sibling.
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