In single time-point sampling qPCR of the whole unilateral kidney and liver at circadian time (CT) 20 ± 2 (mean ± SD; n = 5 control animals), we found no difference in Per2 mRNA expression in mPer2/Gapdh transcript ratio in kidney (control: 0.0024 ± 0.0003, n = 4; CKD: 0.0030 ± 0.0003, n = 5; mean ± SEM; p = 0.18) (Figure 3A), as well as in liver (control: 0.0019 ± 0.0005, n = 5; CKD: 0.0023 ± 0.0001, n = 5; p = 0.21). Here, PER2 is linked to chronic kidney disease.