First systematic experience of preimplantation genetic diagnosis for de-novo mutations

Standard preimplantation genetic diagnosis (PGD) cannot be applied for de-novo mutations (DNM), because neither origin nor relevant haplotypes are available for testing in single cells. PGD strategies were developed for 80 families with 38 genetic disorders, determined by 33 dominant, three recessive and two X-linked DNM. All three recessive mutations were of paternal origin, while of 93 dominant mutations, 40 were paternal, 46 maternal and seven detected in affected children. The development of specific PGD strategy for each couple involved DNA analysis of the parents and affected children prior to PGD, including a mutation verification, polymorphic marker evaluation, whole and single sperm testing to establish the normal and mutant haplotypes and PGD by polar body analysis and/or embryo biopsy. Overall, 151 PGD cycles were performed for 80 families, for which a specific PGD design has been established. The application of these protocols resulted in pre-selection and transfer of 219 (1.72 per cycle) DNM-free embryos in 127 (84.1%) PGD cycles, yielding 63 (49.6%) unaffected pregnancies and birth of 59 (46.5%) healthy children, confirmed to be free of DNM. The data show feasibility of PGD for DNM, which may routinely be performed with accuracy of over 99%, using the established PGD strategy.