Deciding whether to have pre-symptomatic genetic testing: Reasons for wanting to know

Pre-symptomatic genetic testing is available to some people who do not currently have symptoms of MND but have an increased chance of developing it in the future. This section covers:

  • Coming to a decision on pre-symptomatic genetic testing for inherited MND
  • Deciding to have pre-symptomatic genetic testing for inherited MND- reasons for wanting to know

Pre-symptomatic genetic testing (sometimes called ‘predictive testing’) is generally only offered where a genetic variant linked to inherited MND has already been identified in an affected relative. It allows people without symptoms to find out if they have inherited this particular gene variant. Deciding whether to have pre-symptomatic genetic testing is an individual choice, with many factors involved.

Coming to a decision on pre-symptomatic genetic testing for inherited MND

The people we spoke to had different experiences of deciding whether to have pre-symptomatic genetic testing. Some people described their decision as quick and self-evident; they knew almost immediately what they wanted to do. This included people who decided to pursue testing, such as Jade, who “wanted the test 100% from the minute I knew”, and people who did not want to find out their genetic status, like Richard who made the decision “pretty much instantaneously”.

On receiving the news that the C9orf72 genetic variant been identified in her family, Lillian “didn’t pause for a millisecond”. She knew immediately that she wanted to have the pre-symptomatic genetic test.

Georgia had the genetic test shortly after losing her mum and aunt to MND. Looking back, she feels she didn’t think too much about the test, “I think maybe I was so numb from everything that I didn’t even think too much into it… it’s weird, but I just knew that I wanted to know”.

Other people we interviewed weighed up the possible benefits and drawbacks of pre-symptomatic genetic testing for inherited MND. Anthony considered the potential impact of finding out the result versus not knowing, and wrote a pros and cons list. His list of reasons to have the test was a lot longer and after discussing it with his wife he knew quite quickly that he wanted to go ahead.

Calum spent around 18 months considering what he would get out of pre-symptomatic genetic testing. Although he had concerns, he felt these were outweighed by the benefits of knowing.

It is important to note that people’s feelings on pre-symptomatic testing often changed with time and with shifting circumstances. Sam described how over time, they got used to the idea of having a 50% chance of having inherited the gene variant linked to inherited MND, and more recently feel it is “worth the risk” of taking the test. Maggie had an immediate feeling that she was more comfortable not finding out if she had inherited the C9orf72 genetic variant, yet over the next two years her views changed and she decided it would be worth knowing. Another person we spoke to believed that a relative would not have approved of her having the test, yet after they died, she felt “able to make that decision for myself”.

Deciding to have pre-symptomatic genetic testing for inherited MND- reasons for wanting to know

People who had had the pre-symptomatic genetic test spoke of a range of motivations and considerations; most people we interviewed mentioned several reasons which influenced their decision.

Some people found it difficult to live with the uncertainty of knowing that they could have inherited a gene variant associated with inherited MND. Calum tried to put it to the back of his mind and live his life, but he always had a feeling of ambiguity and uncertainty. He believed that spending the next 25 years questioning whether he had inherited it would be worse than knowing he did. Other people described feeling in “limbo”. Jade described herself as someone who likes to “know all the facts” and “get on with it”. Lizbeth wanted a sense of certainty and control. Lillian pointed out that she was already worried by knowing she had a 50% chance of having inherited the C9orf72 gene variant from her father.

Lillian didn’t feel she would be any more worried than she already was if she found out that she had inherited the C9orf72 gene variant.

Another difficulty of living with uncertainty was worrying about possible symptoms. Maggie had experienced periods where she had convinced herself she had symptoms, and started to question whether she could be worrying unnecessarily. For Anthony, the choice around testing was itself a source of stress.

Anthony felt that having the pre-symptomatic genetic test would leave him “better off emotionally”. He wanted to move past the decision and on to the next one.

As Anthony mentioned, the 50% chance of receiving a negative result was an important factor in having the test. Jade and Georgia Z both had a sense that they would receive a negative result; Jade wanted to find out so she could “put it to bed”. Georgia Z described her motivations.

An “instinct” that she would receive a negative result pushed Georgia Z to have the pre-symptomatic genetic test. Having lost her mum and aunt to MND, she thought “what am I really losing?”

For some people we spoke to, having genetic testing was about being prepared and planning ahead. This was often related to having children. Calum and Kelly both wanted children in the future and personally felt they did not want to risk passing on a gene variant linked to inherited MND, or for their children to go through the situation they had of knowing they could have an increased chance of developing MND.

Calum feels grateful to have learnt about reproductive options to prevent his future children from going through what he has gone through. He sees stopping the disease as a “no brainer”.

For Harriet, who had one child when she found out about inherited MND in her family, having the pre-symptomatic genetic test was a “no-brainer”; “we weren’t prepared to continue with our family until we knew the outcome”. Harriet felt it was important to know whether she carried the C9orf72 gene variant to inform decisions on reproductive options, including genetic testing before or during pregnancy.

Having pre-symptomatic genetic testing was also about having concrete information for existing children. Lizbeth and Jade wanted their children to be able to make informed decisions when it came to thinking about having families of their own. As Lizbeth said, “they’ve got far more solid information than I ever did, and I wanted that for them”. One reason Anthony wanted to have genetic testing was to find out if his children could have inherited the C9orf72 gene variant. He can now plan how to talk to them about inherited MND.

For Anthony, planning ahead was also about trying to live a better life in the present, as well as getting involved in things like fundraising. Individuals we spoke to wanted pre-symptomatic testing to inform choices around putting things in place for the future, such as insurance. Other people pointed out that they could do these things anyway, without knowing their genetic status.

People we spoke to also felt that having the pre-symptomatic genetic test would make them better prepared if they were to develop symptoms. Jade hoped this could lead to a faster diagnosis. If a treatment was available, she might be able to have it more quickly.

If she were to develop symptoms, Maggie hoped that being diagnosed early would enable her to join a clinical trial. This was one reason why she changed her mind about having pre-symptomatic genetic testing.

Taking part in research was also important for Anthony. He decided to have genetic testing with a plan to “throw myself into as much research as I could” if he received a positive result.

Even people who had had pre-symptomatic testing had reservations and concerns. Calum initially worried that having a positive genetic test result on his medical history could impact his ability to secure insurance and a mortgage or limit his career. Although it is important to be honest when asked questions by insurance companies about one’s own or a family member’s medical history, Genetic Alliance UK advises that people in the UK do not have to disclose predictive test results for inherited MND.

At first, Maggie felt more comfortable with knowing it was “50:50” whether she had inherited the C9orf72 gene variant from her mother and, before finding out one way or the other, thinking of her children as having an overall 25% chance of having inherited the gene variant (50% x 50%). She later changed her mind.

Although people often felt sure of their choice to have the test by the time they started the genetic counselling process, this was not the case for everyone. Sam felt that they would be able to live a “happy” and “fulfilling” life if they tested positive, but nonetheless questioned whether their decision might change after having genetic counselling.

Sam has “flip-flopped” between a decision on pre-symptomatic genetic testing. Having “come full circle”, they now question whether it is “worth the risk” of taking the test.