Other explanations could be related to interactions with other genes or variants (as reported with ADRB2 in asthma49), environmental factor, or age-related factors (as observed for rs1042713 and cognitive function37) causing a hidden stratification of the sample such that the anxiety phenotype would be associated with either one set of homozygote subjects or the alternate homozygote set57. Here, ADRB2 is linked to Anxiety.