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PGT-M (monogenic disorder)

Preimplantation genetic testing for monogenic disorders (PGT-M)

A single gene disorder is the result of a single mutated gene and there are estimated to be over 4000 human diseases caused by single gene defects e.g. Huntington's disease, neurofibromatosis, cystic fibrosis and sickle-cell anemia. You or your partner, or both of you, may have been made aware that you carry a mutated gene that could lead to a child inheriting a genetic condition. 

PGT-M is a method of testing embryos produced during an IVF treatment cycle for particular genetic disorders before they are transferred to the uterus and is now available for virtually all single gene disorders. The aim of PGT-M is to provide couples at high-risk of passing on an inherited disorder to their children with an improved chance of having an unaffected pregnancy. PGT-M dramatically reduces the likelihood that an affected fetus will be detected during prenatal testing and therefore decreases the probability that parents will face the difficult decision of whether or not to terminate a pregnancy.

Who might benefit from PGT-M?

Any couples who know they are carriers of a serious inherited condition may be interested in PGT-M. Many of those who request PGT-M are fertile and undergo IVF for the sole reason that they wish to avoid an affected pregnancy which may require the possibility of termination.

Step 1: Confirmation and Licensing

As long as a genetic disease has an identified mutation, PGT-M should be possible. Following appropriate genetic counselling and in conjunction with the scientific team at Igenomix we will determine if PGT-M with karyomapping can be done and that the HFEA has licensed the testing of this condition. An HFEA license has to be in place for each condition. It may be necessary to apply for a license for your particular condition and this process can take up to 16 weeks.

Step 2: The Process and the Work Up

PGT-M is achieved through a process called Karyomapping.

The preparation for PGT-M with Karyomapping involves the design of a specific custom-made testing plan and mapping platform for each couple. This will then be able to detect the embryos that are affected and unaffected with the genetic condition being tested for. For this test plan to be designed Igenomix may require blood samples or buccal cells from the couple and potentially other affected family members. The time required for preliminary testing is extremely variable but takes approximately 6 weeks to be made ready for use.

Step 3: Stimulation and Embryo Biopsy

The ovaries are stimulated and eggs are collected and then fertilised using intracytoplasmic sperm injection (ICSI). The use of ICSI reduces the risk of DNA contamination derived from sperm. Embryos will be cultured to the blastocyst stage on day 5 or day 6 where 5-10 cells can then safely be taken from the embryo. The cells are placed in test-tubes and sent to Igenomix by courier. The tested embryos do not leave the IVF clinic, they are immediately cryopreserved (frozen) until test results are available.

Step 4: Genetic testing

The cells are each analysed independently using the patient specific karyomapping method. We can then choose appropriate embryos for transfer based on these genetic results.

No screening test is 100% accurate, so following any genetic screening we recommend that patients who become pregnant, undergo prenatal testing which will reveal whether the genetic diagnosis was correct, and confirm whether or not the foetus is unaffected by the specific disease or mutation.

No screening test is 100% accurate, so following any genetic screening we recommend that patients who become pregnant undergo prenatal testing which will reveal whether the genetic diagnosis was correct, and confirm whether or not the foetus is unaffected by the specific disease or mutation.

Please contact the embryologists in the IVF lab to discuss any further specific needs you may have.

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The Lister Fertility Clinic
The Lister Hospital
Chelsea Bridge Road
London SW1W 8RH

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