Brief Report: Autism Symptoms in Infants with Fragile X Syndrome.
Jane E Roberts, Bridgette L Tonnsen, Lindsay M McCary and 2 others
PMID 27628938WHAT IT FOUND
Fragile X infants at 12 months showed more autism observation signs than typical controls.
In a small sample, 53% were flagged as at risk, versus 17% of infants with an autistic sibling and 6% of controls.
Key findings
01Infants with fragile X were more likely to exceed the autism risk threshold than ASIBs and TD controls: 53% versus 17% and 6%.
02Motor control and atypical motor behavior items showed significant group differences, with higher proportions in infants with fragile X.
03Higher AOSI total scores were associated with higher ADOS severity scores, but the AOSI incorrectly classified 30% of infants with fragile X and 38% of ASIBs.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
This is a preliminary study with a small sample, so group differences need replication. Only male infants were studied, so findings may not apply to females with fragile X, who often have subtler symptoms. ADOS-2 outcomes were missing for 7 sibling-risk infants, 5 infants with fragile X, and 4 typically developing infants, so the follow-up analysis is on a subset. The AOSI categorical risk cutoff incorrectly classified 30% of infants with fragile X and 38% of sibling-risk infants, and false positives were higher in fragile X, so it may not be a reliable clinical screen in this group. The groups differed in developmental age, and mental age was not included in later models because it did not correlate strongly with scores, so this may still affect interpretation. The study is descriptive and does not test treatment or diagnostic outcomes for all participants.
The easy way to misread this
Do not treat a positive autism observation screen in an infant with fragile X as proof of later autism. The study found false positives, including infants with fragile X who screened positive but later scored negative on the autism diagnostic measure.