Study backs wider carrier screening for Fragile X Syndrome

Saturday, Jul 29, 2017, 11:57 PM | Source: Pursuit

By Sylvia Metcalfe

Study backs wider carrier screening for Fragile X Syndrome

Fragile X Syndrome is the most common single gene cause of autism and mothers that carry the mutation can easily be screened for it, but many will never have heard of it, and your doctor is unlikely to mention it when you are pregnant or planning to start a family.

Current guidelines in Australia and around the world recommend testing for FXS only when there is a family history or if women request it. That's because the symptoms can vary from just mild to severe, calculating the genetic risk is complicated, and the only choice a confirmed carrier has is a stark one between having a child or not, or if pregnant, terminating or not.

The problem is, about 1 in every 250 women are carriers, and many of these will have no family history of FXS. These women and couples then are completely in the dark on whether their child is at risk of FXS.

But in a major finding that could lead to wider screening, researchers led by scientists at the Murdoch Children's Research Institute and the University of Melbourne have found that with the right information and genetic counselling, women and couples can easily make informed decisions on whether to take the test.

When provided with information and genetic counselling the study shows that women can and do make informed decisions on whether to screen for Fragile X Sydnrome. Picture: Shutterstock

The study of 1,156 women recruited participants from obstetric and GP clinics, and included both non-pregnant women and women up to 13 weeks pregnant. It found no evidence of increased stress or anxiety as a result of the women having to decide whether or not to be screened for FXS. It also found that over 70 per cent made informed decisions in that they had demonstrated a strong understanding of the issue before making up their minds.

Lead researcher Professor Sylvia Metcalfe says the results provide strong support for increasing awareness of the condition, and being more active in giving women and couples the opportunity to consider being tested. Screening can involve a simple saliva test.

enabling informed decision making

"Whatever decision someone makes on screening is entirely up to them and should be respected, but it is important they are given the information. We are just letting them down if women and couples aren't even hearing about screening for FXS," says Professor Metcalfe.

She noted that three quarters of the women in the study had never heard of FXS.

"What we need to do is raise awareness among people who are considering starting a family and among health professionals. People should be informed that these tests are available and then they should be given time to think about whether they want to be tested or not."

The symptoms of FXS vary but the biggest concern is intellectual disability, which can range from mild in girls to moderate and severe in boys. Symptoms can include anxiety and shyness, Attention Deficit Hyperactivity Disorder (ADHD), autistic behaviours, and learning and communication difficulties. It is estimated that up to 5 per cent of people diagnosed with Autism Spectrum Disorder also have FXS.

Professor Metcalfe says it is important that people aren't pressured into taking such screening tests or stigmatised for their decision, but they have a right to be informed.

"I think that irrespective of what the condition is, we really should be trying to allow people to make informed choices based on their own values and not stigmatising them."

Of the 1,156 women, 756, or 65 per cent, decided to take the test. Of these only three tested positive, and of these two were pregnant. Both elected to continue with their pregnancies following genetic counselling that indicated the risk of FXS in either child was low.

Non-pregnant women were more likely to take the test than pregnant women at a rate of 71 per cent compared to 59 per cent.

Women who elected not to take the test were more likely to make an uninformed choice on the issue. They were also more likely to express regret with their choice, though overall the rates of reported regret were low. Reported rates of depression, stress and anxiety during the decision making process were in line with population averages.

Confronting Unease with information

Screening tests for inherited disorders and diseases aren't publicly funded in Australia or covered by private health insurance, and the cost of being screened for FXS can be around $400, which includes screening for cystic fibrosis and spinal muscular atrophy. "The cost of screening does raise concerns over whether the system is equitable," says Professor Metcalfe.

One of the reasons that information on screening for FXS isn't promoted is partly a function of the unease many feel about the difficult decision that a woman, particularly one who is already pregnant, will face if they do test positive, says Professor Metcalfe. Any decision is further complicated by the fact that the symptoms of FXS can vary widely from child to child, and determining the risk of FXS is highly dependent on someone's individual genetic information.

Testing decisions are further complicated by carriers of the gene mutation being more at risk themselves of early menopause and fertility problems in the case of women, and a risk of a degenerative neurological disease (Fragile X-associated tremor/ataxia syndrome) that is more likely to affect male carriers.

"There has always been discomfort around screening for a condition that is primarily an intellectual disability and behavioural problem. It is also a complex condition because there is a whole range of risk and potential symptoms.

"But the women in this study were able to understand the complex information provided through pre-test counselling and written information, and this helped them to make an informed decision."

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