PGD

Developed in the early 1990's, preimplantation genetic diagnosis (PGD) is a way for couples to prevent a pregnancy affected by a genetic condition or chromosomal disorder. There are various types of PGD available, depending on the needs of the individual couple. This form of genetic testing is performed on eggs or embryos during an in vitro fertilization (IVF) cycle. The eggs or embryos that have been analyzed and are found to be normal are transferred into the woman's uterus, where, hopefully, they will implant and result in the birth of a healthy child.

 

Currently, we are able to perform PGD for many genetic conditions including single gene disorders and chromosomal abnormalities. We also use PGD to determine the sex of an embryo during gender selection. We pioneered the polar body removal technology and are one of the most active centers offering PGD in the world. Our laboratory staff has extensive experience in the techniques involved with PGD.

 

How can PGD help me?
PGD can significantly reduce the chances for your baby to be affected with a specific genetic condition or chromosomal abnormality. We are able to test for many different diseases, including aneuploidy, single gene disorders and chromosome translocations.

 

Many couples request PGD for aneuploidy such as Down syndrome, trisomy 18, trisomy 13 and Turner syndrome. These disorders do not typically run in families. However, up to 60% of early miscarriages are due to aneuploidy, and the risk for aneuploidy increases with a woman's age. The purpose of PGD for aneuploidy is to increase a couple's chance for pregnancy, reduce their risk for miscarriage, and improve their overall chance of bringing home a healthy baby after in vitro fertilization.

 

Other couples request PGD for a specific genetic condition that may run in their family, such as Tay Sachs disease, cystic fibrosis, muscular dystrophy, Fragile X syndrome or spinal muscular atrophy. Our center has extensive experience testing for many single gene disorders, including rare genetic syndromes.

 

For individuals who carry a chromosomal translocation, PGD can be used to test eggs or embryos for their specific translocation. This greatly decreases the risk for miscarriage and/or the birth of a child with birth defects and mental retardation associated with an unbalanced chromosome translocation.

 

We can also test for the HLA status of embryos. This is requested by couples interested in having a child who is a healthy bone marrow match to another family member. HLA testing can be performed while testing for a specific genetic condition, such as beta-thalassemia.

What conditions are tested with PGD?
The conditions tested include:

•Aneuploidy
•Single Gene Disorders
•Translocations
•Gender Selection

 

How is PGD performed?
Our geneticists use a variety of techniques for PGD including:

•Polar Body analysis
•Embryo analysis

 

At present,  Yulane Fertility Solutions working with RGI is the only center in the world offering Preimplantation Diagnosis by sampling the first and second polar bodies. The first polar body is naturally discarded during oocyte maturation, prior to fertilization and contains one set of duplicated chromosomes (with two chromatids in each chromosome), while the second polar body is naturally discarded after fertilization and contains one set of chromatids. By testing the first and second polar bodies for a specific genetic disease, the geneticists can determine whether the woman's eggs carry the normal or abnormal copy of the corresponding gene. The procedure is offered to couples who are known carriers of a genetic disease detectable by DNA analysis.  Yulane Fertility Solutions working with RGI physicians have already performed thousands of clinical cycles involving preimplantation diagnosis for cystic fibrosis, thalassemia, Tay-Sachs disease, sickle cell disease, and other single gene disorders, resulting in many ongoing pregnancies confirmed to be unaffected by tests during pregnancy (CVS or amniocentesis) or after birth.

 

The other important application of the polar body testing is preimplantation diagnosis of Down syndrome and other common aneuploidies. Many patients referred to an In Vitro Fertilization program (IVF) are of advanced maternal age (35 years of age or older at the time of delivery), which places them at elevated risk for conceiving a child with an extra chromosome and thus delivering a child with Down syndrome (extra chromosome 21) or other common trisomies (trisomy 13 and 18). Aneuploidies may also result in spontaneous abortions (miscarriage) or nonimplantation, considerably decreasing the chances of the patient achieving a pregnancy. Therefore, by testing for the conditions beforehand, we can decrease the chances for spontaneous miscarriage and failed implantation and increase the chance of achieving pregnancy. Polar body analysis involves the removal of the first and second polar bodies for testing by FISH. Only embryos with a normal number of the chromosomes that are studied (for example, chromosomes 13, 16, 18, 21, and 22) are transferred. The patients may choose which embryos they wish to be transferred or frozen. The procedure has been offered to thousands of IVF couples and resulted in the birth of hundreds of healthy children confirmed to be unaffected by CVS or amniocentesis. This has also improved the pregnancy rate, compared to patients of advanced maternal age without polar body analysis.