Having children free of HSP
How does IVF help someone with HSP have children without them inheriting the condition?
There are different ways to prevent a child being born with a serious genetic condition. This may be the case for HSP which is a progressive, incurable, and potentially disabling disorder. The decision to take measures to have a child free of HSP is entirely a personal one. It may be helpful to consider this issue well before starting a family, and to start discussions with your partner, family, and health professionals.
Preimplantation genetic diagnosis (PGD) or preimplantation genetic testing is a sophisticated technique which can be used to prevent children from inheriting HSP. PGD can be used when one or both parents have a known genetic abnormality (in this case an HSP mutation). Testing is performed on an embryo created through the IVF process to see if it also carries the mutation(s) in the HSP gene. Only embryos that do not have the mutation(s) are selected.
There are other options as well, including testing during a pregnancy with amniocentesis or chorionic villus sampling (prenatal testing). Some people may prefer PGD to prenatal testing, due to the emotional and health impacts of terminating a pregnancy.
You may also choose not to undertake any genetic testing of the pregnancy; the decision is up to you.
What is IVF actually … what is the process?
IVF (In Vitro Fertilisation) is a procedure undertaken in a specialised laboratory, where the egg and sperm and joined outside the body. The fertilised egg, or embryo, is grown before being implanted in the uterus. After this process there is a chance that a pregnancy will occur. IVF is often performed for couples with fertility issues.
Can it help anyone with HSP have children free of the condition?
PGD can be performed for a variety of circumstances, and it is important to have a discussion with your doctor to see if it is relevant for you. However, it can only be performed if the HSP genetic diagnosis is known. One important factor will be the mode of inheritance of HSP, or the way it is transmitted. For example, for autosomal dominant forms of HSP (i.e. a mutation in a single copy of the gene), such as mutations in SPAST (SPG4), ATL1 (SPG3A), or REEP1 (SPG31), there will be a 1 in 2 (50%) chance of passing the mutation on without PGD or prenatal testing.
On the other hand, if you have autosomal recessive HSP (mutation on both copies of the gene), such as SPG11, SPG15, SPG7, or SPG5A, your children will be carriers of a single mutation but will likely not get the condition, unless your partner also has the condition or is also a carrier.
If both you and your partner are carriers of an autosomal recessive type of HSP, you have a 1 in 4 (25%) chance of passing on the condition to your children. This situation may come to attention if you have already had a child with HSP.
These issues can be complex and difficult to understand, and it is best discussed with a clinical geneticist or genetic counsellor so that you are in a good position to make an informed choice.
So I need a conclusive genetic test for HSP … what if the genetic test result finds something that only might be causing HSP?
This can be difficult to decide what to do. In some cases, a decision may be made to do PGD, with the knowledge that this is a risk reduction measure. However, this is very uncertain situation and requires detailed discussion with a genetic counsellor or clinical geneticist.
Where do I start, who do I see to work out if it is possible in my situation?
Talk with your health professionals. In this case, a general practitioner would be a good place to start. You may have a neurologist and they are also a good person to ask. There are many specialist neurogenetic clinics in major cities who will have knowledge about this situation. Furthermore, a referral to a genetic counsellor or clinical geneticist may be appropriate.
How long does it take? How much does it cost? What are the chances of success?
It may be best to ask these questions to an IVF specialist. Certainly, IVF and PGD can have a large out of pocket cost, and the chance of success may vary according to many factors such as the age of the mother.
How do I choose a clinic?
Check with your GP, genetic counsellor or clinical geneticist about which clinic to choose. It is worth remembering that not all IVF clinics will have expertise in PGD.
There is now a website with information to help you choose a clinic: https://www.yourivfsuccess.com.au/
I have a child with HSP who is now 20 and in a serious relationship. Should I talk with them about IVF? When? How?
It would be a good idea to let your child know that there may be ways of preventing HSP from being passed on to their children, that this is optional, and that they can discuss this issue with their health professionals. I think it is best to start the conversation as soon as possible to allow for forward planning, and to allow your child to make an informed decision.
With thanks to Dr Kishore Kumar, neurologist, for his input to this article.
Here are some older articles on IVF published on the website:
June 2013: https://hspersunite.org.au/family-planning-and-hsp/ (personal story)
September 2013: https://hspersunite.org.au/family-planning-and-hsp-2/ (personal story)
June 2016: https://hspersunite.org.au/a-new-era-in-genetic-testing-for-hsp/ (genetic counsellor and paediatric neurogeneticist)