North Shore Fertility's preimplantation genetic diagnosis program (PGD) is on of the most extensive in the area for couples who are at risk of transmitting genetic diseases to their children. Diseases such as hemophilia, cystic fibrosis, sickle cell anemia, and others have a genetic or "chromosomal" basis. In the past, "carrier" couples ran a high risk (in some cases 50%) of transferring serious diseases to their offspring and often did not attempt pregnancy. We receive referrals for PGD from throughout the world.
When PGD is used with in vitro fertilization it allows the physician to determine if the pre-embryos are normal, and advise the couple, before it is placed back into the uterus.

The "at risk couple" undergoes a standard IVF cycle and the resultant eggs are combined with sperm and placed in an incubator. Normally, the father contributes 23 chromosomes and the mother contributes 23. Sometimes this "combining" process occurs improperly leading to potential birth defects or pregnancy loss. Chromosomes may also be damaged.
In PGD, once the embryos have reached the stage where they are ready to be transferred, a biopsy is taken by "drilling" a hole in the outer membrane (zona pellucida) and removing a single cell.

Chromosomes are examined using include fluorescent in situ hybridization (FISH) and/or the polymerase chain reaction (PCR). FISH involves labeling the chromosomes with a fluorescent tag allowing them to be examined by the embryologist. PCR enables making multiple copies of the DNA segments for examination. Large chromosomal abnormalities, such as extra or missing chromosomes (aneuploidies), gender determination, and unbalanced chromosomal translocations, resulting from a parental balanced translocation, can be detected by fluorescence in situ hybridization (FISH). PCR creates multiple copies of specific identified areas of the chromosome and is used to screen for single gene defects. When the genetic disease is present in the parent, a copy of a segment of his/her gene can be used to make a genetic probe. This probe will “identify” the genetic disease if it is present in the embryo.

The chromosomes are counted, the number of X and Y chromosomes is verified, and other structural problems are identified. The end result is the transfer of embryos known to be chromosomally normal.

PGD can be used to screen for the following diseases and others:

Gender Selection

The PGD FISH technique is very effective in identifying male and female embryos after IVF making it effective for gender selection. In fact, gender selection success rates approach 100% using PGD.  If the couple desire a male child, only male embryos identified using PGD are transferred to the uterus.  This technique is very effective in screening for sex linked genetic diseases as discussed above.