Preimplantation Genetic Diagnosis Process
IHR provides effective on-site preimplantation genetic diagnosis treatment.
IHR is co-located with RGI, the only PGD center in the world currently offering Preimplantation Genetic Diagnosis by sampling the first and second polar bodies. The first polar body is 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 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 corresponding gene. The procedure is offered to couples who are known carriers of genetic diseases detectable by DNA analysis. IHR physicians have already performed over 100 clinical cycles involving preimplantation diagnosis for cystic fibrosis , thalassemia, Tay-Sachs disease, sickle cell disease, and other diseases, resulting in many ongoing pregnancies confirmed to be unaffected by CVS or amniocentesis as well as the birth of two dozen healty children. 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. If you have any questions as you review the material on preimplantation genetic diagnosis, please contact us for a FREE Preimplantation Genetic Diagnosis E-Mail Consultation.
Chromosome abnormalities (aneuploidies) are associated with failed implantation, pregnancy loss, and the birth of children with multiple congenital anomalies. Preimplantation genetic diagnosis (PGD) provides a means of testing for these chromosome abnormalities and selecting the best embryos for transfer. Embryos with chromosome abnormalities are almost always physically indistinguishable from healthy embryos; therefore, without PGD, abnormal embryos are equally likely to be transferred, reducing the chances of achieving a viable and healthy pregnancy.
Prior aneuploidy testing involved 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 or child.
Research shows, however, that 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.
IHR performs 24-chromsome analysis 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), blastomeres (from Day 3 embryos), or blastocyst/trophectoderm (from Day 5 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. Results are concise and reliable, and our genetic counselors are available to provide clear interpretation of the data.
The other important application of the polar body testing is preimplantation diagnosis of Down syndrome and other common aneuploidies. Many patients referred to 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, decreasing considerably the chances of the patient achieving a pregnancy. Therefore, by testing for the conditions beforehand, we can prevent these events. Polar body removal involves the removal of the first and second polar bodies and analysis of the chromosome number in both the first and second polar body by FISH. Only embryos resulting from the fertilization of eggs with normal number of the chromosomes (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 over 600 IVF couples and resulted in 131 births of healthy children and dozens ongoing pregnancies 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 diagnosis.
We also offer Preimplantation diagnosis based on blastomere biopsy. The most common application of blastomere biopsy is preimplantation sexing by FISH to avoid the pregnancy with X-linked disorders, such as hemophilia A and muscular dystrophy, or for single gene disorders in which the male partner is affected.
IHR has treatments for a variety of conditions, including unexplained infertility, ovulatory dysfunctions, endometriosis, immunological infertility and many others. Perhaps less known is our work with individuals and couples who are considering assisted reproduction, but who are uncertain of their next step. We encourage anyone, before they make a decision, to consult with us. Currently, we are offering a FREE Preimplantation Genetic Diagnosis E-Mail Consultation.