FYI Research: Screening for fragile X syndrome
If your newborn carried an incurable condition, would you want to know?
When Don Bailey puts this question to parents of kids with fragile X syndrome, most say, yes, they wish they’d known what was coming sooner. But when researchers offer screening for fragile X to new parents at UNC Hospitals, less than two-thirds of parents take them up on it.
Bailey and UNC researchers in the Fragile X Newborn Screening Study want to know how the parents make their choices, and how those whose newborns test positive for fragile X deal with the news.
“Fragile X is an inherited genetic disorder,” said Bailey, research professor in the School of Education and the FPG Child Development Institute and a Distinguished Fellow at RTI International. “It’s passed down from generation to generation through carrier parents. Most of them have no clue that they’re carriers.”
About 1 million people in the United States carry the gene, and 100,000 of them have the mutation that leads to fragile X syndrome, the most common known cause of autism and the most common cause of inherited mental impairment.
The learning problems and developmental delays often don’t show up until the third year of a child’s life. There is no cure. But there are treatments that, if given early, can help the children and their families for the rest of their lives.
Some babies with fragile X syndrome suffer sensory and attention problems throughout infancy. Left untreated, the problems manifest themselves as tantrums, aggression or withdrawal. Individualized support programs including speech, music and physical therapy; early childhood special education; and help with motor development can help the children be calmer and more focused.
But by the time most babies are diagnosed with fragile X syndrome, their families have missed out on those early treatments.
Screening newborns for fragile X syndrome is controversial, Bailey said. DNA tests can show that a baby carries the mutated gene, but not the level of impairment the child will eventually suffer. Tests can also identify babies who have a “pre-mutation” version of the gene, which could be passed on to cause fragile X syndrome in future generations.
If there’s no cure, some parents say, is it worth disrupting those first few months of parenthood, worrying about problems their child may develop later? Some critics say that routine screening could lead to hyper-vigilant parenting or postpartum depression.
But these assertions have no evidence to support them, so Bailey and his colleagues are now offering screening to new parents at UNC Hospitals and analyzing how families respond and adapt when a newborn with the gene is identified.
“Each family takes a different path,” Bailey said. “Eventually they may consult with a medical geneticist and genetic counselor; they may go to the Internet to read more about fragile X; they sometimes call people at the National Fragile X Foundation to learn more about what to expect. They inform other members of their family who may be at risk. They also start thinking about their other children and deciding whether to have them tested.”
The study recruiters offer screening just after the mothers have given birth and before the parents leave the hospital. “They have a short window of time to understand the material and make a decision,” Bailey said. And researchers can’t perform the heel-prick blood test unless both parents agree to it.
The fragile X study touches on a larger controversy over genetic testing for newborns, Bailey said.
Newborns are routinely tested only for specific, treatable, life-threatening conditions. But some researchers say that whole-genome testing for newborns would be a far better way to help doctors find other serious health problems (including fragile X) early, before symptoms even begin to show up.
The question is whether the benefits of foresight and early intervention would outweigh the drawbacks.
“With whole-genome screening for newborns, we’d be put in a really challenging position, because we’d learn hundreds of things about that baby,” Bailey said. “What do you disclose and what do you not disclose?”
The fragile X screening study (www.fpg.unc.edu/~fxnewborn) is a partnership between Carolina and RTI International. Other Carolina researchers include Debra Skinner, a senior scientist at the FPG Child Development Institute; Cynthia Powell, an associate professor and chief of the Division of Genetics and Metabolism in the Department of Pediatrics; and Myra Roche, an associate professor in the Department of Pediatrics.