Hida A, Kitamura S, Katayose Y, Kato M, Ono H, Kadotani H, Uchiyama M, Ebisawa T, Inoue Y, Kamei Y, Okawa M, Takahashi K, Mishima K. Sci Rep. 2014 Sep 9;4:e6309.
In order to assess the relationship between genetics and chronotype, the authors performed a study involving 1174 subjects recruited from medical centres in mainland Japan. The subjects were genotyped and given the Horne–Östberg Morningness–Eveningness Questionnaire to determine their chronotype.
It found that having the per3 SNP rs228697 is associated with being a morning chronotype, as well as being a free running chronotype. However, these results may simply be false discoveries since the significance tests for association were not adjusted for the many tested hypotheses.
rs228697 in per3