Objective
The purpose of this study is to evaluate the clinical aspects and the efficiency of Preimplantation Genetic Diagnosis (PGD) for single gene disorders combined with HLA matching in order to obtain an unaffected child who can be an HLA donor for its sibling.

Design
A retrospective study from a tertiary clinic.

Materials and methods
Overall 21 couples with 26 cycles were included with single gene disorders and a history of an affected child. 23 couples with β Thalassemia, 1 cycle with Wiscott Aldrich Syndrome and additional 2 cycles for only HLA matching for Acute Lymphoblastic Leukemia (ALL). A total of 206 embryos were biopsied, 31.5% of embryos were found to be mutation free, 42.7% were heterozygous embryos, 15.5% of embryos were found to be HLA compatible but affected, only 12.6% of embryos were found to be unaffected and HLA matched. Mutation analysis was carried out using Minisequencing method. HLA typing was realized with STR analysis after fluorescent PCR. The cases were evaluated according to the female age and ovarian reserve.

Results
Out of 22 females aged below 35 years, 16 had embryo transfers. The others were cancelled due to the lack of HLA compatible embryos. A total of 7 pregnancies were achieved (43.7%). The rate of implantation was 27.7%. One pregnancy resulted in miscarriage (14.3%). However for females aged above 35 years, all 4 embryo transfers were cancelled due to the limited number of embryos suitable for HLA testing. In 18 cases with normal ovarian reserve, 14 had embryo transfers, 6 pregnancies were achieved (35%); however in cases with diminished ovarian reserve (n=8), only 1 had embryo transfer and the pregnancy resulted in early abortion.

Conclusion
Our preliminary data implies that the possibility of finding both disease-free and HLA compatible embryos is negatively related with the number of embryos available for the analysis. Since in most cases, these couples are fertile, a patient’s ovarian reserves as well as the selection of an optimum hyperstimulation protocol primarily determine this variable. Once suitable blastocyst-stage embryos are available for transfer, they may result in acceptable clinical pregnancies. Therefore, couples seeking this treatment options should be informed about such limitations before a PGD and preimplantation HLA typing procedure is sought.