Guy's Hospital in London offers preimplantation genetic diagnosis for many genetic conditions. Genetic counsellor Genevieve Say reports the team is happy to consider referrals from cardiomyopathy patients if certain criteria are met
Suffering from cardiomyopathy can impact on many aspects of life. Furthermore, if the condition is part of a genetic syndrome, other family members may be affected or at risk.
Cardiomyopathy is a feature of many genetic syndromes. One of the most common concerns people express when they see us in the genetics clinic is the risk of passing on the syndrome to their current or future children. In some cases the risk can be as high as 50 per cent.
Genetic testing is becoming possible for an increasing number of genetic conditions and is sometimes available in pregnancy.
Some couples opt for prenatal testing (testing in pregnancy), which can lead to difficult choices if the pregnancy is found to be affected. For some couples, prenatal testing and termination of an affected pregnancy is not acceptable.
To avoid having to make such decisions in a pregnancy, a reproductive option that is becoming more widely available is preimplantation genetic diagnosis (PGD). PGD is a technique available to some couples who are at high risk of having children affected with a serious genetic condition. The aim of treatment is to help them conceive an unaffected pregnancy.
PGD involves the use of IVF technology to create embryos in the laboratory, using the couple’s eggs and sperm. Each embryo is then tested and only embryos that are unaffected with the genetic condition will be considered for transfer to the womb. The first PGD cycle was performed about 20 years ago, but it is only in recent years that PGD is becoming more widely used as the technique becomes increasingly more sophisticated.
Guy’s Centre for Preimplantation Genetic Diagnosis integrates our genetics department and our assisted conception unit. We are the leading PGD centre in the UK and one of the most successful units in Europe. We offer PGD for many genetic conditions and have had over 250 unaffected babies born following treatment.
As cardiomyopathy has many causes, we are not able to test embryos for this disease itself. However, we currently offer PGD for genetic conditions such as Marfan syndrome and 22q11 deletion (DiGeorge) syndrome, both of which are associated with cardiomyopathy. Furthermore, we are happy to consider referrals for other cardiomyopathy syndromes as requested, if certain criteria are met.
To offer PGD for a new condition, we would assess the severity of the condition, its genetic basis, the couple’s family history and their suitability for IVF treatment. If we are able to proceed, we then need to apply for a specific disease licence from the Human Fertilisation & Embryology Authority (HFEA) and design the test in our laboratory, all of which takes significant extra time on top of the routine process.
Our referral criteria require that the female partner is within a healthy weight range and under the age of 39 (or under the age of 37 if referred for a new condition to allow for the extra time required for set up). We need genetic testing to have been done in the family to confirm the genetic basis of the condition. And because of the technique that our laboratory uses to set up PGD, we need to have access to fresh blood or stored DNA from the couple and at least one other affected family member.
Unfortunately PGD treatment is not routinely covered by the NHS and requires applying for funding on a case-by-case basis. However, the good news is that around 80 per cent of our couples who meet certain criteria have been granted NHS funding in the past.
While PGD removes some of the difficult issues surrounding prenatal diagnosis, it is not an easy option. Because of the set-up required, it is often a year after the first appointment before a couple are able to start treatment (and longer for new conditions).
Furthermore, as PGD involves using invasive fertility treatment (even though many couples do not have fertility issues), the success rate is relatively low compared with the chances of conceiving naturally.
Of all patients who start treatment, approximately one in five will achieve a successful ongoing pregnancy. If treatment progresses to the point that a good quality embryo is transferred to the womb, the chances of success increase, with approximately one in three transfers resulting in a successful ongoing pregnancy.
We always look forward to our couples announcing the delivery of a healthy baby following treatment, happily an increasingly more frequent event.
However, PGD is a complex, time consuming and sometimes expensive process. We therefore advise couples to think very carefully about whether it is the right way forward for them.
If you are interested in discussing PGD further, we would need a written referral from your local genetics unit. You could also look up our website for more details (www.pgd.org.uk)
If you wish to find out about other centres offering PGD, then it is best to contact the HFEA. They have details of other licensed centres around the UK and the treatment offered (see www.hfea.gov.uk)
Dedicated to Damian McLoughlin, who died age 20 of cardiomyopathy. This site is supported by Damian's family and friends.
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