Translocations

Gene Security Network (GSN) now offers the first widely available PGD test to simultaneously evaluate aneuploidy across all 24 chromosomes and inherited unbalanced chromosome rearrangements such as those arising from parental reciprocal translocations and inversions.

TECHNOLOGY

Parental Support technology provides the most comprehensive PGD for translocation and inversion carriers. Historically testing has been performed using florescent in-situ hybridization (FISH) technology to create telomeric probes for the relevant chromosomes. A significant shortcoming to this method is the inability to evaluate all other chromosomes simultaneously. This can lead to the transfer of an embryo that may be free of an unbalanced structural rearrangement, but fails to implant or miscarries due to sporadic whole chromosome aneuploidy.

Parental Support™ technology uses over 300,000 microarray measurements to evaluate aneuploidy across all 24 chromosomes in addition to detecting inherited unbalanced chromosome rearrangements. Results are returned the morning of Day 5 for Day 3 blastomere analysis, and in about one week for Day 5 trophectoderm analysis. Since balanced structural rearrangements are indistinguishable from normal chromosomes, results for both states are reported out as ‘normal’.

HOW DO I GET TESTING?

Testing for unbalanced chromosome arrangements requires prior approval from the GSN laboratory team. This review and approval process is performed at no cost. To begin this review process, please see the section “Steps to GSN Testing for Translocation, Inversions, and other Chromosome Rearrangements” above or contact us directly for more information.

BACKGROUND

Individuals carrying a balanced chromosome rearrangement are at increased risk to create eggs or sperm — and resulting embryos — with an unbalanced chromosome state. Pregnancies with unbalanced chromosome rearrangements are frequently lost in miscarriage, or can result in the birth of a baby with birth defects and mental retardation. In some couples the parental chromosome rearrangement may contribute to infertility due to failed implantation. Structural chromosome rearrangements are identified in approximately 3-5% of couples who have experienced recurrent pregnancy loss (RPL).

One treatment option for patients who carry structural chromosome rearrangements is to undergo in vitro fertilization (IVF) and PGD to identify embryos with normal or balanced chromosome complements. These embryos can then be selectively transferred to the patient. Couples with balanced rearrangements who undergo PGD have a significantly decreased risk of miscarriage and chromosomally abnormal liveborns.[ Lalioti MD Curr Opin Obstet Gynecol 2008, Lim CK, Fertil Steril 2008]

Find a list of GSN’s Partner IVF Clinics testing for Translocations nearest you.

WHAT’S NEXT?

1. Find a Partner IVF Clinic that GSN works with; if you are already working with an IVF clinic that GSN is not currently working with, please send an email to info@genesecurity.net with the contact information of the clinic and the name of the doctor that you are working with.

2. Once working with a Partner IVF Clinic, ask your IVF physician for GSN testing and he or she will send in a referral. You will also need to send in a copy of your karyotype report to GSN for evaluation

3. GSN will evaluate the karyotype and notify the IVF physician within one week of receipt whether the case can be accepted.

4. Upon acceptance, GSN will contact you to schedule a genetic counseling appointment (there is no cost for this consultation, and no commitment required to continue with GSN testing) – this is your opportunity to ask any technical questions you may have about Parental Support results and benefits compared to other available preimplantation genetic testing technologies.

5. You will receive a GSN parent collection kit which is used to gather data from the egg and sperm contributor for each case. Once you have decided to proceed with testing you will sign the included consent forms and you can submit blood or buccal samples directly to GSN.

6. After the above steps are complete, you are ready to have your IVF cycle with GSN’s Parental Support technology for translocations, inversions, and chromosome rearrangements.