PER2 and cancer: This is not surprising, given that polymorphisms in this gene could increase the risk of developing certain cancers and have been associated with sleep disorders [50].The association between asthma and sleep disorders could explain the high level of circadian CLOCK-related gene expression (PER2 and GCR) and the high interaction activity of the TIMELESS gene in PPIs for the moderate-to-severe asthma phenotype (Figure 4C).