- Single Gene Disorders are those of known chromosomal origin where a single or multiple gene defect on a specific chromosome can lead to the presence of a certain disease in a fetus.
- Translocation Disorders occur when pieces of chromosomal DNA break off and reattach to other chromosomes. In most cases these can lead to chromosomal rearrangements not compatible with life or result in repeated miscarriages.
- Aneuploidy Disorders occur when extra or missing chromosomes during fertilization and replication lead to significant genetic abnormalities such as Down’s Syndrome (Trisomy 21 or three copies of chromosome 21 instead of the normal two).
PGS and PGD techniques permit the selection and subsequent transfer of embryos which are less likely to have chromosomal abnormalities or free of a known single gene disorder, hence increasing the chances for a successful pregnancy, decreased risk of miscarriage, and healthy baby. This is the same process also allows for family balancing (elective gender selection) and medically indicated gender selection.
What Are the Steps With PGS or PGD?
Patients who need PGS or PGD will undergo a typical IVF cycle at Advanced Fertility Care. After the patient’s eggs are retrieved, they are fertilized with the husband’s or donor sperm in the laboratory. The lab waits for fertilization to occur and lets the embryos develop for 5 to 6 days into the 80-100 cell blastocyst stage. At the blastocyst stage, our embryologist will remove three to four cells from each embryo after creating a precise microscopic hole in the outer shell with a laser (embryo biopsy) and then prep these cells for secure transport to a specialized genetic reference labs for the chromosomal analysis. The embryo-specific results will then be communicated back to the embryologist and physicians at Advanced Fertility Care.
Once chromosomally normal embryos are confirmed, patients will then be coordinated for a frozen embryo transfer after appropriate ovarian suppression and uterine preparation using hormonal stimulation. The frozen embryo transfer can occur as soon as 5-6 weeks after initial egg retrieval but this is dependent on several factors. In most cases, Advanced Fertility Care Physicians will subsequently only transfer at the most two blastocysts and in most cases, recommend transfer of one chromosomally tested normal blastocyst in order to avoid the increased risk of higher order multiples.
Will I Need PGS/PGD With My IVF Cycle?
Not all patients that undergo IVF need PGS or PGD. There are a number of factors that help determine whether genetic embryo screening may be of benefit:
- Known family history for structural chromosome rearrangement or particular genetic diseases such as Cystic Fibrosis, Huntington’s Disease, and Tay Sach’s Disease. There are actually hundreds of known genetic diseases which we are able to screen for and this number is increasing all the time as the human genome project continues.
- Maternal Age: All women have a risk to have a pregnancy with a chromosome abnormality. This risk increases as a woman’s age increases. Prenatal diagnosis by chorionic villus sampling (CVS) or amniocentesis to test for chromosome abnormalities, such as Down syndrome, is also available post conception, however, PGD/PGS enables patients to determine risk prior to implantation of embryos. There are many recent and ongoing studies that have indicated a significant increase in overall pregnancy outcome for women over age 35 who utilize PGS technology in conjunction with IVF. For women under age 35, PGS is still an option, especially for family balancing reasons, however, overall benefit to increased pregnancy outcomes is still considered controversial. For those who are interested in considering PGS with IVF, we encourage an open and frank discussion with your physician regarding the pros/cons for your particular situation.
- Recurrent Pregnancy Loss: About 50% of first trimester miscarriages are due to a chromosome abnormality. This may be related to a woman’s age or a rearrangement in a parent’s chromosomes that predisposes the couple to conceive pregnancies with chromosome abnormalities. PGS can be performed for either of these possibilities.
- Prior Pregnancy With Chromosome Abnormality: Patients that have had a previous chromosomally abnormal pregnancy have an elevated risk for a similar problem to occur again in any subsequent pregnancy regardless of maternal age.
- Several Failed IVF Cycles: Some cases of IVF failure are due to the transfer of embryos with chromosome abnormalities. PGS for aneuploidy minimizes the likelihood of a chromosome abnormality in a future pregnancy and increases the chance of achieving an ongoing successful pregnancy.
- Family Balancing (also known as Sex Selection): For families that wish to have additional children of a particular gender after already having a previous child, PGD allows for selection of embryos to transfer based on gender. While not perfect, embryo biopsy with genetic chromosome determination prior to transfer of embryos can allow families choice in how they expand the family.
The genetic laboratories which are utilized by Advanced Fertility Care all offer screening for chromosomal abnormalities on all 24 chromosome pairs which can provide information on translocations (abnormal placement of chromosome materials) as well as aneuploidy (abnormal number of chromosomes).
While great tools in reproductive medicine, PGS and PGD are not foolproof and not ideal for all situations. In your consultation, Dr. Zoneraich and Dr. Larsen will discuss the pros and cons of utilizing this genetic testing as it pertains to your specific circumstances.
Costs of PGS or PGD
In addition to the cost of the IVF procedure used to retrieve eggs and create the embryos for testing, there are two additional components that contribute to the overall costs of performing genetic testing on embryos. The first cost is the actual cost of the technique and time for the embryologist to biopsy (remove cells from) the embryos. The second cost is that of the genetic analysis of the cells that are sent to the genetics laboratory.
Since every situation may be unique, we encourage you to call our office at (480) 874-2229 in order to discuss the costs that would pertain to your specific situation.
Interested in PGS or PGD – Next Steps
If you are interested in scheduling an appointment to discuss the option of PGS or PGD along with IVF, please contact our office or call to schedule an appointment in one of our 3 convenient locations.