Recently, Fourier et al. (2017) found a significant association of CLOCK gene rs12649507 with CH (p = 0.0069, OR = 1.29, 95% CI = 1.08~1.54) in a large Swedish CH case-control sample (449 patients and 677 controls) [29], strengthening the hypothesis of the involvement of circadian rhythm in CH. The gene discussed is CLOCK; the disease is cyclic hematopoiesis.