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pgd faqs

PGD FAQs
IHR provides effective preimplantation genetic diagnosis treatment.

If you have any questions as you review the material on preimplantation genetic diagnosis, please contact us for a FREE PGD E-Mail Consultation.








What is preimplantation genetic diagnosis (PGD)?
Preimplantation genetic diagnosis (PGD) is diagnosis of a genetic condition of an embryo prior to achievement of a pregnancy. This form of genetic testing is performed on eggs or embryos during an in vitro fertilization (IVF) treatment. This allows parents to avoid the very difficult dilemma of aborting an affected pregnancy or raising a sick child. We can offer PGD by sampling the first and second polar bodies, single blastomere biopsy from a 3-days old embryo, or by trophectoderm biopsy (cells that will develop to be the placenta and not from the embryo – like a very early CVS) from embryos that developed to blastocysts (day5-6 embryos with 70-80 cells). Currently, we are able to perform PGD for almost any known genetic disease, including single gene disorders, chromosomal abnormalities, mutations in the mitochondrial genome, for a variety of cancer predispositions genes, and HLA matching.

Why come to IHR for PGD?
Dr. Tur-Kaspa, IHR’s Medical Director, conducts personally hundreds of IVF/ICSI treatment cycles annually for infertility, and personally conducted more than 1000 IVF-PGD cycles in the last few years for patients with over 50 different single gene genetic disorders (such as Cystic Fibrosis, Fragile-X syndrome, Muscular Dystrophy, Thalassemia, Sickle cell anemia, Huntington disease, and Hereditary cancer predisposition genes), chromosomal translocations, for HLA matched child, and for aneuploidy, with very high success rate. Currently, we are able to perform PGD for almost any known genetic conditions including single gene disorders and/or for chromosomal abnormalities. IHR collaborate with the Reproductive Genetic Institute, a word known Chicago based PGD laboratory. The IHR’s IVF-PGD teamwork closely with couples undergoing the many different types of assisted fertility treatments and PGD methods available. We are renowned for our specialized knowledge and high IVF success rates even in difficult cases. IHR's expertise in preimplantation genetic diagnosis lies in our willingness and ability to individualize our approach to best suit each and every one of our patients.

What are chromosomes?
Chromosomes are the structures in our cells that carry our genetic information or genes. Our genes determine our physical makeup, growth and development. Normally, we have 46 chromosomes in each cell. Our children inherit 23 chromosomes from each parent, in the egg and sperm. A woman’s risk for having an abnormal number of chromosomes in her eggs increases with her age. Preimplantation genetic testing will detect the most common chromosomal abnormalities found during pregnancy, such as Down syndrome, trisomy 13 and trisomy 18.

Can PGS help me?
Preimplantation genetic screening (PGS) refers to techniques where embryos from presumed chromosomally normal genetic parents are screened for chromosomal abnormalities (aneuploidy conditions). Many couples request PGD for aneuploidy, such as Down syndrome, and trisomy 18 or 13. Aneuploidy conditions typically do not run in families. However, 60-80% of early miscarriages are due to aneuploidy conditions, and the risk for aneuploidy increases with a woman's age. The purpose of PGS 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. Same test is also used for gender balancing. PGS can be performed by analysis of a single cell by fluorescence in situ hybridization (FISH), using probes for a limited number of chromosomes. FISH testing is able to detect the most common chromosome abnormalities, including Down syndrome, Trisomy 18, Trisomy 13, and sex chromosome anomalies, in order to reduce the risk of having an affected pregnancy.

Research, abnormalities involving any chromosome can increase the risk of miscarriage and reduce the effectiveness of IVF. IHR’s new 24-chromosome testing is able to analyze the entire chromosome complement of a single cell, reducing the risk of failed implantation and miscarriage, and increasing the chance of having a healthy baby. Recent prospective randomized trials showed that when embryos are biopsied at the blastocyst stage (day 5-6) and tested by PGS for 24 chromosomes, embryo implantation and delivery rates improved significantly.

IHR offer 24-chromsome analyses using a technique called microarray, or array comparative genome hybridization (a-CGH). This technique compares the amount of DNA present for each chromosome in a single cell, and compares it to that of a normal standard. Microarray can be performed on three different sample types: polar bodies (from fertilized eggs), blastomere (from Day 3 embryos), or trophectoderm cells from a blastocyst/Day 5-6 embryos). Embryo transfer during the same cycle is feasible for polar body and/or blastomere testing, whereas trophectoderm testing typically requires embryo freezing and thawing for transfer at a later date. With today freezing technology, outcome of frozen-thawed embryo transfer is as good or even better than of fresh transfer.

How is PGD performed?
There are two basic types of preimplantation diagnosis—polar body analysis and embryo analysis. Both types have their advantages and their limitations. Polar body testing focuses on the maternal contribution, and is an earlier method of testing which in some instances may have a higher accuracy. Embryo testing accounts for both maternal and paternal genetic contributions but occurs later and may not be as accurate.

What are polar bodies?
Polar bodies are the byproducts of the egg’s division. As an egg matures, it goes through a two-step division process, dividing once at the before fertilization (when ovulation would occur) and again after fertilization. The two polar bodies are the products of these 2 divisions, and are essentially being discarded by the egg (oocyte). Both polar bodies are removed on the day after egg retrieval and fertilization. By analyzing the polar bodies, it is possible to infer the genetic status of the oocyte.

What is an embryo biopsy?
Biopsy for PGD, especially if performed at experienced centers of the polar bodies (small particles with the genetic mirror image of the egg) or trophectoderm biopsy on day 5-6 at the blastocyst stage (embryo with 70-80 cells), seems to have no significant short-term or long-term impact and may be used safely for embryo biopsy without notably reducing the pregnancy and delivery rate. Biopsy on day 3 embryos (6-8 cells) is now considered less optimal. The cell that is removed may then be analyzed to determine directly the genetic status of the embryo.

Does PGD replace prenatal testing?
PGD does not replace prenatal testing, such as chorionic villus sampling or amniocentesis. PGD test allows for a similar diagnosis to those available by prenatal testing, with a major advantage that it can be performed before pregnancy. However, prenatal testing is still recommended, as this is still the standard of care, and to confirm the PGD results. The genetic consoler will discuss what prenatal testing options are available to you.








If you have any questions as you review the material on preimplantation genetic diagnosis, please contact us for a FREE PGD E-Mail Consultation.