FMR1 and attention deficit-hyperactivity disorder: FMR1 mRNA expression was significantly higher in participants with at least 1 SCID-5 diagnosis (median difference 1.98 vs 0.87, P = 0.0017), in those with ADHD (2.30 vs 2.04, P = 0.009), in those with depression (2.19 vs 1.98, P = 0.025) and in those with at least 1 FXAND condition (2.16 vs 1.94, P = 0.005).