Objectives: The retinoid-related orphan receptor A (RORA) gene has been reported to have an impact on circadian rhythm regulation. In this study, we analyzed the relationship between the RORA gene polymorphism and diurnal preference in Korean young adults. Methods: A population of 504 young adults was included in the study. All subjects were given and completed a 13-item composite scale for morningness (CSM). The RORA gene rs11071547 single-nucleotide polymorphism (SNP) was genotyped by PCR-based methods. Results: CSM score was not associated with genotype or allele carrier status of the RORA rs11071547 SNP. Conclusion: This result indicates that the RORA rs11071547 SNP does not play a role in diurnal preference. Sleep Medicine and Psychophysiology 2016；23(1)：25-28

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