What is Fragile X Syndrome?
A person may be fully affected by the genetic condition but not show all of its symptoms and characteristics. Video: Supplied
The first time Kerry Moore heard about fragile X syndrome she was sitting in the developmental paediatrician's office with her 12-month-old son.
Her first-born, Oliver, had missed important milestones – he was slow to crawl, walk and speak – and Ms Moore had just learnt what was wrong.
"I had no idea. It came out of nowhere," Ms Moore said.
"I was in complete and utter shock and there were so many emotions that I was feeling. Guilt was a big one, because I passed it on to my baby."
The genetic condition causes intellectual disability and behavioural and learning challenges, and is also the most common single-gene cause of autism worldwide.
Women who are carriers are at the greatest risk of having a child with the syndrome, and about one in 250 women in the general population are carriers.
And yet, only a few have heard about the syndrome, and even fewer are screened for it.
Testing for carriers is available privately, but current guidelines do not recommend carrier screening to women without a family history, because of concerns about the complexity of information and the potential for psychological harm.
Now a new study by the Murdoch Children's Research Institute suggests all women should be told about screening for the genetic condition – preferably before starting a family. – as long as they are well informed and receive support in making their decision.
The study, which was published recently in the international journal Genetics in Medicine, was conducted over three years and involved 1000 Australian women who were pregnant or planning a family.
Lead researcher Professor Sylvia Metcalfe said the best practice was to enable informed decision-making about a condition that was relatively common.
"All women are at risk of being a carrier," Professor Metcalfe said.
"[Bu] it is complex in how it is inherited and how the gene itself causes fragile X syndrome.
"The length of the gene [FMR1] is associated with having the condition. So if you are a carrier, you have a medium-length gene ... and the longer gene is associated with fragile X syndrome."
However, Professor Metcalfe said the chance of the carrier gene becoming a longer-length gene when passed on to the child was not the same for everyone.
"It is an individual risk," she said.
Professor Metcalfe said screening to determine whether someone is a carrier, particularly before starting a family, would give women more choices, including using IVF with an embryo tested before being implanted.
She said women who were carriers could also have their own health problems, including early menopause.
Ms Moore, who now has two more boys, one using IVF, said she wished she had known she was a carrier before starting her family.
"Oliver [now aged 15] is very family oriented and he has lot of love. That helps us deal with it," she said.
"Knowing that you are carrier before you have children means the choices are open to you.
"You can make plans, it is not such a shock when you have a newborn baby."