"Pre-Implantation Genetic Diagnosis (PGD) as Both a Diagnostic"
Pre-Implantation Genetic Diagnosis (PGD) as Both a Diagnostic and Therapeutic Tool in Assisted Reproductive Technology (ART) Lawrence Werlin, M.D. IVF success rates are dependent on a variety of factors, including the age of the oocyte, embryo quality, and endometrial lining receptivity. Recently, we have begun to look directly at the embryo from a genetic standpoint evaluating its chromosomal make-up in an effort to improve IVF success. PGD allows us to evaluate the chromosomal make-up of an embryo, or to screen for a specific single gene defect, such as cystic fibrosis, before placing the embryo into the uterine cavity. Previously, chorionic villa sampling, or amniocentesis were the established methods used to evaluate the abnormalities. Unfortunately, these tests are only performed after pregnancy has been achieved. The Genesis Network for Reproductive Health, funded by an ongoing educational grant from Organon Inc., has conducted the first IRB approved, randomized, prospective study evaluating the effectiveness of PGD in three high-risk groups of patients at greater risk for genetically abnormal (aneuploidy) embryos. The three high-risk groups include: 1. Recurrent Pregnancy Loss (RPL) 2. Advanced Maternal Age (AMA) 3. Repeated Failed Cycles (FC) The data was published in Fertility and Sterility in August of 2003. Initially, it was clear that PGD offered no benefit in the FC group. It appeared that the trend may be beneficial in the RPL and AMA groups, however the numbers were small. Subsequently, the study has been expanded and continued in an effort to better evaluate the RPL and AMA groups to reach statistical significance. A total of 76 patients were enrolled from August 1, 2001 through April 1, 2004. All patients were randomized into either controls or PGD. All underwent stimulation protocols using Follistim and Antagon (Organon, West Orange, NJ). At the appropriate time, Pregnyl (hCG) 10,000 IU (Organon) was administered. Approximately 34-36 hours after hCG administration, ultrasound guided oocyte retrieval was performed. Intracytoplasmic sperm injection was performed on all mature oocytes. In the PGD group, embryo biopsy and blastomere fixation were done on day 3 post retrieval on all 6-8 cell embryos, with only one cell biopsied per embryo in most cases. Slides were sent to Reprogenetics for fluorescence in situ hybridization analysis for chromosomes 13, 15, 16, 17, 18, 21, 22, X and Y. Results were received on day 4 post retrieval. Embryo transfer (ET) of only the chromosomally normal embryos was done on day 5 post retrieval. In the control group, ET was performed on day 3 or 5 post retrieval based on physician preference. In both the PGD and control groups, corticosteroids, low-dose aspirin (80-81 mg), and progestational supplementation were used. Serum B-hCG levels were obtained 12 days after ET. Pregnancy was confirmed by demonstrating at least two appropriate consecutively rising B-hCG levels. 65 ART RESOURCE DIRECTORY 2006 Pre-Implantation Genetic Diagnosis (PGD) as Both a Diagnostic and Therapeutic Tool in Assisted Reproductive Technology (ART) Lawrence Werlin, M.D. Overall, in both groups, 68% of embryos biopsied were Dr. Lawrence Werlin, a nationally noted specialist in reproductive abnormal. Approximately 23% of the women had no endocrinology and infertility, is the founder and Medical embryo transfer due to all embryos being abnormal. Director of Coastal Fertility Medical Center, and co-founder of GENESIS Network for Reproductive Health In the RPL/PGD group, 45.5% achieved pregnancy with Contact information: an implantation rate of 21%, as compared to 41.2% Coastal Fertility Medical Center pregnancy rate with an implantation rate of 14% in 4900 Barranca Parkway, Suite 103 controls. In the AMA/PGD group, 30% achieved Irvine, CA 92604 pregnancy with an implantation rate of 10%, as Phone: 949-726-0600 compared to 17.6% pregnancy rate with an implantation Fax: 949-726-0601 rate of 11% in controls. In conclusion, a number of findings Email: firstname.lastname@example.org were evident: Website: http://www.coastalfertility.com 1. It was re-confirmed that in both groups of INCIID member profile: http://www.inciid.org/members patients, PGD may be beneficial, since there is member.php?cust_id=10278 a tendency toward higher pregnancy and implantation rates. 2. PGD confirms that aneuploidy is a common cause of RPL. 3. In view of the large numbers of abnormal embryos in each group, couples may consider alternative options earlier, such as donor oocytes, donor embryos, and/or adoption. Though PGD appears to be a beneficial tool, there are various caveats to be considered. Although relatively small, the risks include: 1. False-positive results 2. False-negative results 3. Arrested development of the embryo Also, at the present time, the greatest limitation of PGD is that we can only safely look at 9 to 10 specific chromosomes, previously mentioned above, for aneuploidy. These chromosomes make up approximately 85% of all aneuploidies that occur. The remaining 14 chromosomes are not screened. Newer technologies such as Comparative Genomic Hybridization (CGH), will allow us to screen all 23 chromosomes. Finally, there is obvious concern that ethical standards must be applied to the use of PGD. Strict guidelines for its uses must be established. Further discussion will ensue to address these important issues. ART RESOURCE DIRECTORY 2006 66