Preimplantation genetic diagnosis (PGD) involves screening single cells from embryos for genetic diseases and chromosomal disorders. This testing is performed with in-vitro fertilization (IVF)  and occurs prior to embryo transfer, before a pregnancy is established. PGD offers at risk couples the opportunity to select embryos for transfer based on their genetic and chromosomal status. The goal of PGD is to identify abnormal embryos so they will not be transferred , leaving unaffected embryos to be selected for transfer that are more likely to make healthy, disease free babies.

PGD can identify the presence of chromosomal translocations (rearrangements of parts of chromosomes) and single gene disorders ( genetic diseases that are a result of a single mutated gene). There are over 4000 single gene disorders. The most common diseases tested for are Cystic fibrosis , Tay Sachs, Fragile X, Myotonic dystrophy and Thalassemia.

PGD technology can also be used to determine the sex of the transfer into the uterus.

What is Preimplantation genetic Screening (PGS)

For those people with recurrent pregnancy loss or infertility , PGS applies the technology from PGD to improve their chances for a successful pregnancy. Embryos are screened for aneuploidy (missing or additional numbers of chromosomes) , which  is a leading cause of miscarriage and implantation failure (failure of embryo to implant into the uterus). The goal of PGS is to identify chromosomally abnormal embryos , so they will not be transferred leaving the chromosomally normal embryos to

be transferred in the attempt to achieve a successful pregnancy.