It is well established that the oldest chronotype questionnaire, the morningness-eveningness questionnaire (MEQ), has significant heritability, and several associations have been reported between MEQ score and polymorphisms in candidate clock genes, a number of them reproducibly across populations. By contrast, there are no reports of heritability and genetic associations for the Munich chronotype questionnaire (MCTQ). Recent genome-wide association studies (GWAS) from large cohorts have reported multiple associations with chronotype as assessed by a single self-evaluation question. We have taken advantage of the availability of data from all these instruments from a single sample of 597 participants from the Brazilian Baependi Heart Study. The family-based design of the cohort allowed us to calculate the heritability (h²) for these measures. Heritability values for the best-fitted models were 0.37 for MEQ, 0.32 for MCTQ, and 0.28 for single-question chronotype (MEQ Question 19). We also calculated the heritability for the two major factors recently derived from MEQ, “Dissipation of sleep pressure” (0.32) and “Build-up of sleep pressure” (0.28). This first heritability comparison of the major chronotype instruments in current use provides the first quantification of the genetic component of MCTQ score, supporting its future use in genetic analysis. Our findings also suggest that the single chronotype question that has been used for large GWAS analyses captures a larger proportion of the dimensions of chronotype than previously thought.

众所周知，最古老的时间型问卷，早晚问卷 (MEQ)，具有显着的遗传性，并且已经报告了 MEQ 分数与候选时钟基因多态性之间的几种关联，其中一些在人群中可重复。相比之下，没有关于慕尼黑时间型问卷 (MCTQ) 的遗传力和遗传关联的报告。最近来自大型队列的全基因组关联研究 (GWAS) 报告了通过单个自我评估问题评估的与时间表的多种关联。我们利用了来自巴西 Baependi 心脏研究的 597 名参与者的单一样本的所有这些仪器的数据可用性。队列的基于家庭的设计使我们能够计算遗传力（h ²) 这些措施。最佳拟合模型的遗传力值对于 MEQ 为 0.37，对于 MCTQ 为 0.32，对于单问题表型（MEQ 问题 19）为 0.28。我们还计算了最近从 MEQ 得出的两个主要因素“睡眠压力消散”（0.32）和“睡眠压力累积”（0.28）的遗传力。目前使用的主要计时工具的首次遗传力比较提供了 MCTQ 评分遗传成分的首次量化，支持其在遗传分析中的未来使用。我们的研究结果还表明，用于大型 GWAS 分析的单一时间型问题比以前认为的捕获了更大比例的时间型维度。