Genetic Testing of Embryos
Preimplantation Genetic Diagnosis and Chromosomal Screening of Embryos
When genetic health concerns may be an issue, Pacific NW Fertility is proud to offer the most advanced diagnosis and screening techniques available. The two most common types of genetic testing are to test patients for single gene disorders (i.e. genetic mutations) that could be passed on to their children, and to test embryos for genetic abnormalities that may occur within the embryo's initial development.
Learn more about genetic testing from these two helpful videos from Genesis Genetics:
Single gene disorder testing for patients planning to conceive
The goal of this type of testing is to screen patients for genetic mutations that could be passed on to their children. Examples of the diseases that can be detected with this type of testing are cystic fibrosis, spinal muscle atrophy, Tay Sachs disease, and more. For these type of diseases – we have to know before the IVF cycle if patients carry these mutations in order to know to look for them within the embryos. Knowing that you are a carrier for a genetic mutation allows the option of testing embryos (during an IVF cycle) for a specific genetic mutation before any embryos are transferred. The testing involves a blood test for patients and Pacific NW Fertility is proud to work with Counsyl for the analysis and interpretation of these results.
The blood is drawn at PNWF and sent to Counsyl for DNA analysis and screening of over 100 genetic mutations. Please note that science does not allow testing for all possible diseases and by doing this screening, you are decreasing risk, not eliminating it. If patients test positive for any mutations – they are referred to a board-certified genetic counselor in order to interpret results and answer questions – a complimentary option through Counsyl.
Chromosomal Screening (CS) for embryos
The goal of this type of testing is to ensure the correct number of chromosomes (46) are present in each embryo. The typical number of chromosomes in a human cell is 46 - two pairs of 23 - holding an estimated 25,000 genes. One set of 23 chromosomes is inherited from the biological mother (from the egg), and the other set is inherited from the biological father (from the sperm). Embryos with a normal chromosomal count are more likely to result in a healthy full-term pregnancy. An incorrect number of chromosomes may result in Down’s syndrome (3 copies of chromosome number 21) or miscarriage (up to 70% of miscarriages tested show chromosomal errors).
During an IVF cycle, several cells from each blastocyst (an embryo that has been developing for 5 to 6 days) are biopsied by our own highly trained embryologists. These cells are sent to Genesis Genetics for analysis to ensure that only embryos free of identified risks will be transferred into the patient’s uterus. The embryos are then frozen with an advanced technique called vitrification and stay at Pacific NW Fertility and IVF Specialists during the entire process. Genesis Genetics utilizes a process called Genesis-24, a procedure designed to examine all chromosomes before any embryos are transferred so that you can make informed and confident decisions as you move forward with your family planning. The number of specific genetic disorders for which CS may be helpful is nearly unlimited and the list is continually updated.
Waiting for the CS results and conceiving in a future cycle has significant benefits for the patients. In addition to screening for the most viable embryos available in an IVF cycle, it allows time for the patient to recover from ovarian stimulation. Studies have shown that transferring embryos into a uterus with a more natural hormonal environment may allow for a higher chance of conception. Studies also support freezing the embryos with vitrification does not decrease success with implantation.
Patients who may consider Preimplantation Genetic Screening (PGS) also known as Chromosomal Screening (CS) of their embryos:
- Women age 38 and older ( increasing age of eggs associated with higher percentage of embryos with chromosomal imbalances)
- Increased success rates with single embryo transfer (decreasing risk of multiple gestation)
- Women with a high response to IVF stimulation (a high number of embryos for transfer – chromosomal screening can select embryos with the highest chance of success)
- Unexplained Infertility and/or failed IVF cycles without chromosomal screening of embryos in the past
- Recurrent pregnancy loss (most common cause of first trimester miscarriage is chromosomal imbalance in the embryos)
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