No association of CLOCK 3111T/C polymorphism with diurnal preference and sleep quality in Korean adults

초록

The CLOCK 3111T/C polymorphism has been associated with evening preference, but most of the following studies did not replicate the original finding. Although several studies suggested that the sleep quality was also influenced by genetic factors, the relationship of CLOCK 3111T/C polymorphism with sleep quality has not been identified in general population. We aimed to examine whether there is a difference in CLOCK 3111T/C polymorphism according to the morningness-eveningness in Korean adults, and to find a difference in sleep quality according to this polymorphism. Forty-five morning type (MT) (age: 43.93 +/- 12.51 years, M:F = 14:31), 59 neither type (NT) (age: 35.20 +/- 9.53 years, M:F = 20:39), and 52 evening type (ET) (age: 29.08 +/- 7.94 years, M:F = 15:37) subjects were finally selected after excluding those with sleep disorders or shift work. The CLOCK 3111T/C was analyzed by DNA sequencing or SNaPshot assay. The genotype distribution, C allele frequency, and proportion of C allele positive subjects were significantly different between the MT, NT and ET groups. There was no significant difference in PSQI scores between the subjects with TC genotype and age-, sex-and ME type-matched subjects with TT genotype (n = 15 for each group). It is difficult to say that our result replicates the previous finding that showed an association of CLOCK 3111C allele with evening preference, for there was no subject with CLOCK 3111CC homozygote in our study. Moreover, the hypothesis that CLOCK 3111T/C polymorphism may be associated with sleep quality was not supported by our study.

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