Fragile X syndrome (FXS), more research needed


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To read on AAP (American Academy of Pediatrics) website:

Early identification, treatment of fragile X remain public health, clinical concerns

Amanda E. Bennett, M.D., FAAP and Leah Burke, M.D., FAAP    June 1, 2017

A supplement in the June issue of Pediatrics ( summarizes current knowledge regarding fragile X syndrome (FXS) and reinforces the pediatrician’s role in early identification and working with families to improve outcomes and quality of life.

Pediatricians are called on to identify those with FXS early by ordering a fragile X DNA test for both male and female patients with a wide range of medical, cognitive/developmental and psychiatric issues associated with FXS. The evidence also reinforces how pediatricians can help coordinate care/therapies and provide psychopharmacological interventions.

Consider the case of an 18-month-old boy who was referred by his pediatrician to a developmental specialist because of global developmental delays. Despite the parents’ efforts to schedule an appointment as soon as possible, they had to wait six months. When they finally had their appointment, the developmental pediatrician suspected fragile X syndrome and referred the boy for genetic testing, which was another six-month wait. During this lengthy process, the family had a second child.

Shortly before the patient’s third birthday, a genetic test confirmed FXS, around the same time the boy’s brother started to exhibit developmental delays. It turned out the brother also had FXS. If the parents had learned earlier about their older son’s FXS diagnosis, they would have been able to make a fully informed decision about expanding their family, including the risks of having more children with FXS.

More research needed

FXS is the most common inherited cause of intellectual disability and accounts for an estimated 2%-6% of autism spectrum disorder cases. Studies estimate that one in 4,000-5,000 males and one in 6,000-8,000 females have FXS, but those numbers are based on small samples.

FXS is a rare condition, so many pediatricians may never have encountered a patient with FXS or may be unfamiliar with the signs of FXS, leaving some patients undiagnosed. If more patients with developmental or intellectual delays were tested for FXS, the prevalence could be higher.

According to the supplement “Fragile X Syndrome,” early identification and treatment of FXS remain important public health and clinical concerns. The supplement, which is a result of a stakeholder meeting held by the Centers for Disease Control and Prevention, identifies six areas in which additional research could benefit FXS patients and families: 1) epidemiology, 2) early identification and screening, 3) impact on individuals and families, 4) FXS across the lifespan, 5) co-occurring conditions, and 6) interventions and outcome measures.

Importance of genetic testing

The average age that a child is diagnosed with FXS is 3 years. FXS symptoms vary, making it difficult to diagnose patients without a genetic test. Some patients with FXS have dysmorphic features, but others never develop these features or may not start to develop them until puberty. In addition, emotional, behavioral, motor, sensory, learning and social development for FXS patients can range from normal to severely impaired.

In the last 20 years, technology for genetic testing has vastly improved. If a child exhibits intellectual or global developmental delays, a referral for further assessment or early intervention can be helpful, but a simultaneous referral to genetic testing can prevent families from being caught in a diagnostic odyssey.


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