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. Author manuscript; available in PMC: 2021 Oct 27.
Published in final edited form as: N Engl J Med. 2021 May 20;384(20):e76. doi: 10.1056/NEJMc2104154

Circadian Mechanisms in Medicine

Hugo Y-H Lin 1, Ming-Yu Yang 2, Sheng-Fung Lin 3
PMCID: PMC8549064  NIHMSID: NIHMS1747043  PMID: 34010542

To the Editor:

Allada and Bass (Feb. 11 issue)1 provide a comprehensive review of circadian mechanisms in medicine, focusing on physiology, molecular circuitry, and the contribution of circadian processes to disease. Although circadian misalignment causes disease, epigenetic modifications of circadian gene expression are also influential and usually involve DNA methylation at CpG sites (locations in DNA at which a cytosine precedes a guanosine in the 5′ to 3′ sequence).2–4 DNA methylation plays a crucial role in embryonic development and across the human lifespan, including the recovery of persons with circadian disorders.4 However, according to our previous research,5 methylation is not temporary. Methylated CpG sites are prominent in patients with chronic myeloid leukemia (CML). The treatment of patients with CML could reactivate JUNB, an activating protein 1 transcription factor that is important in the control of cell growth and differentiation and neoplastic transformation. Epigenetic modifications of circadian genes should be viewed as central to certain disease processes.

Footnotes

No potential conflict of interest relevant to this letter was reported.

Contributor Information

Hugo Y.-H. Lin, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan

Ming-Yu Yang, Chang Gung University, Tao-Yuan, Taiwan

Sheng-Fung Lin, E-Da Hospital, Kaohsiung, Taiwan

References

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