Polar body-based preimplantation genetic diagnosis for Mendelian disorders.

Introduced >20 years ago, the use of polar bodies (PBs), involving sequential removal and genetic analysis of the first (PB1) and second (PB2) PB, provides the option for pre-embryonic diagnosis, when the objection to the embryo biopsy procedures makes preimplantation genetic diagnosis (PGD) non-applicable. PB-based approach has presently been utilized in PGD for genetic and chromosomal disorders, applied either separately, or together with embryo biopsy approaches, especially if there are two or more PGD indications. We present here the world's largest experience of 938 PGD cycles for single-gene disorders performed by PB testing for 146 different monogenic conditions, which resulted in the birth of 345 healthy children (eight pregnancies are still ongoing), providing strong evidence that PB-based PGD is a reliable and safe procedure, with an extremely high accuracy rate of over 99%. With application of microarray technology, PB-based approach will be utilized for increasing number of indications, involving simultaneous testing for 24 chromosomes and single-gene disorders.