In the Kover et al.’s (2013) study, which was focused on examining the predictors of the age-related trajectory of IQ in adolescents with FXS, autism symptom severity was found to predict the intercept (i.e., level at the first assessment) of IQ; however, no prediction was afforded by autism symptom severity after FMRP levels were controlled, which also suggests that the FMRP-autism symptom severity is mediated by IQ. This evidence concerns the gene FMR1 and autism.