Fig. 1
Gene-by-gene interaction in measures of depression in fibromyalgia subjects (FMS) (n = 81) and anxiety in all participants (n = 120). a FMS displayed a significant 5‐HT1A-by-5-HTT interaction in HAD-D (Hospital Anxiety and Depression Scale, Depression subscale) scores and b BDI (Beck’s depression inventory) with 5‐HT1A CC paired with the 5-HTT high expressing genotype resulting in lowest depression values. c A similar pattern was observed in STAI (State-trait anxiety inventory) data obtained from all participants (FMS and healthy controls) with both STAI-S (state subscale) and d STAI-T (trait subscale) displaying serotonin-relevant gene–gene interactions in addition to significant group differences (see Additional file 3: Fig. S1). Plotted are black circles, triangles and squares representing estimated marginal means with 95% confidence interval combined with colored boxplots, with the line representing the median, the upper and lower box representing the 25th (Q1) and 75th (Q3) percentile, i.e. the interquartile range (IQR), and whiskers represent Q1− and Q3 + 1.5*IQR. Raw data is plotted in the background