Despite the documented links between FMR1-related variation and depression in the FMR1 premutation, a number of studies have failed to detect molecular genetic correlates of anxiety in this group [70, 72, 77, 84, 86, 95, 96] and extant findings suggest a complex, multifactorial, epigenetic basis to anxiety symptom expression. This evidence concerns the gene FMR1 and major depressive disorder.