Short tandem repeats haplotyping of the HLA region in preimplantation HLA matching

Recently, preimplantation genetic diagnosis ( PGD) has been considered for several indications beyond its original purpose, not only to test embryos for genetic disease but also to select embryos for a nondisease trait, such as specific human leukocyte antigen ( HLA) genotypes, related to immune compatibility with an existing affected child in need of a haematopoetic stem cell ( HSC) transplant. We have optimized an indirect single-cell HLA typing protocol based on a multiplex fluorescent polymerase chain reaction ( PCR) of short tandem repeat ( STR) markers scattered throughout the HLA complex. The assay was clinically applied in 60 cycles from 45 couples. A conclusive HLA-matching diagnosis was achieved in 483/530 ( 91.1%) of the embryos tested. In total, 74 ( 15.3%) embryos revealed an HLA match with the affected siblings, 55 ( 11.4%) of which resulted unaffected and 46 ( 9.5%) have been transferred to the patients. Nine pregnancies were achieved, five healthy HLA-matched children have already been delivered and cord blood HSCs, were transplanted to three affected siblings, resulting in a successful haematopoietic reconstruction.