ASD Comorbidity in Fragile X Syndrome: Symptom Profile and Predictors of Symptom Severity in Adolescent and Young Adult Males.

The final analysis included 44 of 58 eligible males, and excluded participants were more impaired on expressive syntax, so the sample may not represent more impaired individuals. The sample was not population based and was limited to males with FXS who had at least phrase speech and could travel to testing sites. The study used concurrent measurements, so it cannot show whether expressive syntax, IQ, psychiatric symptoms, or mosaic status cause ASD symptoms. The predictors explained only a modest amount of variance, with no adjusted R2 exceeding .20. Nonverbal IQ scores were very low and restricted, with many participants at the floor, which limits how much IQ variation could be tested. ADOS-2 scores were computed using the upper age limit of the module because many participants were older than the norming sample. FMRP analysis had technical limitations related to collection, storage time, and analysis. The study used only one measure for each construct, so the relationships may not replicate with different measures. No intervention was tested, so the paper cannot show that treatment changes ASD symptoms.

Do not conclude that improving expressive syntax will reduce autism symptoms in fragile X syndrome. The study measured associations concurrently, and the predictors explained only a modest amount of variance.