Preimplantation genetic testing with HLA matching: from counseling to birth and beyond

Preimplantation genetic testing-human leukocyte antigen '(PGT-HLA) only' refers to the HLA typing of single or few cells biopsied from in vitro fertilized preimplantation embryos. The aim of the procedure is to establish a pregnancy, in which the fetus is HLA compatible with an affected sibling in need of a hematopoietic stem cell transplantation (HSCT). During PGT-M-HLA, the identification of a HLA-compatible embryo is combined with the detection of mutation(s) underlying immunodeficiencies and hemoglobinopathies. We report a combined retrospective and prospective cohort analysis of PGT-(M-)HLA procedures carried out from 1998 until 2017, with follow-up of transplantations to 2019. During the study period, 234 couples from 22 countries were invited for a multidisciplinary consultation. Two couples were rejected and 70 couples declined (various reasons), leaving 162 couples for which 414 clinical cycles were carried out. Cleavage stage biopsy followed by single-cell multiplex PCR for short tandem repeat-based haplotyping was applied in most cases (98.7%). The diagnostic efficiency was high (94.8%) but only 16.5% of the embryos was genetically suitable for transfer. Fresh and frozen-thawed embryo transfer resulted in 67 clinical pregnancies, 63 deliveries, and 74 live births, of which 60 children were HLA compatible. This yielded a live birth delivery rate of 30.3% per transfer. Information on neonatal characteristics of the matching PGT-(M-)HLA children showed reassuring outcomes. So far, HSCT was carried out successfully for 25 out of 26 cases. In conclusion, our data show that PGT-(M-)HLA is a valuable procedure: the high complexity and limited delivery rate are balanced by the successful HSCT outcome and the positive impact on families.