Despite efforts to increase awareness, children are often age 3 or older before they are diagnosed with fragile X syndrome, a new study finds.

Researchers say there’s been practically no change in the age of diagnosis over the last seven years in the study published online in the journal Pediatrics.

Fragile X is the most common way a person can inherit intellectual disability. The disorder is not obvious at birth and can take years to be noticed without genetic testing. Without this knowledge, parents often give birth to a second child with the disorder.

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“Awareness of fragile X syndrome has grown as a result of research, statements by professional organizations and advocacy,” said Don Bailey of RTI International who is the study’s lead author. “However, changing the age of diagnosis will be difficult without broader and more systemic changes in pediatric practice.”

The study looked at over 200 families with children who have fragile X and found that boys tend to be diagnosed around 35 to 37 months while girls are generally diagnosed after 41 months.

In more than a quarter of cases, families had a second child born with fragile X before learning of the first child’s diagnosis.

“Routine genetic screening for fragile X syndrome, which would significantly benefit children and their families, would be accelerated by the development of a cheap and accurate screening test,” Bailey said.