Objective
The objective of this study is to present the experiences of Turkey on preimplantation genetic diagnosis (PGD) of single gene disorders (SGD) with or without HLA typing.

Design
A retrospective study from a tertiary clinic.

Materials and methods
Overall 98 cycles were performed for totally 74 couples. 61 of these were for SGD combined with HLA typing applied to 44 couples, 6 of them were for only HLA typing applied to 5 couples. Remaining 31 PGD cycles were applied for 13 different SGDs including β thalassemia (n=10), sickle cell disease (n=5), cystic fibrosis (n=3), Familial Mediterrenean Fever (n=2), Glucose6PhosphateDehydrogenase Defficiency (n=1), mucoploysaccharidosis (n=1), Neuro Fibromatosis Type1 (n=1), San Filippo Disease (n=3), Spinal Muscular Atrophia (n=4), Spastic Paraplegia (n=1). External and nested PCR amplification was performed on the spare blastomeres. Mutation analysis was done using the Minisequencing method. First and second polar bodies were biopsied for the aneuploidy testing for patients over 37 years old. Alternatively aneuploidy testing was also done using flourescently labelled STR markers in case no results were obtained from the polar body study.

Results
Totally 876 blastomeres were biopsied and 140 of them were transferred to the mother. Out of 67 cycles for HLA typing 37 embryo transfer cycles were performed. 30 embryo transfer (ET) cycles were cancelled due to lack of HLA compatible embryos. The average age of these cases were 32.3. Average embryos transferred is 1.6. Totally 12 pregnancies (33.3%) were obtained out of 36 ET cycles (pregnancy result of 1 cycle was not received when this report was prepared). Four live births were obtained from 3 pregnancies (3 from β thalassemia and 1 from WAS) while 2 pregnancies are continuing. The 3 affected children were totally cured after the transplantation of haematopoietic stem cells obtained from the cord blood of their HLA compatible healthy siblings. For PGD of only SGDs, totally 31 cycles were performed in which 30 ET cycles were done. One embryo transfer (ET) cycle for FMF was cancelled because the one embryo studied was diagnosed as affected. Average age of the women in these cycles were 32.2. Overall 12 pregnancies (41.4%) were obtained from 29 ET cycles (1 cycle is not included in the statistics because the ET was done during the preparation of this report). Average number of embryos transferred is 2.7. Two pregnancies resulted in live births and 6 pregnancies are continuing.

Conclusion
Our results show the successful diagnosis of single gene disorders and application of HLA typing on the embryos using spare blastomeres with two step PCR. Despite the lower probability of finding suitable embryos for embryo transfer, the data presented in this report shows the feasibility and the practicibility of PGD-HLA application. It can be concluded that the application of PGD in combination with HLA typing seems to be a promising and effective theurapatic tool for an affected sibling.