Broms Ulla, Silventoinen Karri, Madden Pamela A F, Heath Andrew C, Kaprio Jaakko
Department of Public Health, University of Helsinki, Finland.
Twin Res Hum Genet. 2006 Feb;9(1):64-72. doi: 10.1375/183242706776403046.
Both genetic and environmental factors affect smoking initiation and maintenance, but less is known about the genetic architecture of various other smoking-related behaviors. The aim of this study is to examine the genetic architecture of smoking behavior in a large twin cohort. Questionnaires with an extensive smoking history section were mailed to same-sex adult twins of the Finnish twin cohort. The final study population included 2923 monozygotic and 6018 dizygotic twin pairs aged 24 to 88 years. Two-stage bivariate genetic modeling of age at initiation with amount smoked (less than 20 cigarettes per day vs. 20 or more) and age at initiation with smoking cessation was done by using the Mx statistical package. For men the heritability estimate for age at initiation was .59 (95% confidence interval [CI] .49-.69), for amount smoked .54 (95% CI .45-.62) and for smoking cessation .58 (95% CI .50-.65). For women the heritability estimates were .36 (95% CI .28-.43), .61 (95% CI .46-.70) and .50 (95% CI .39-.60), respectively. The genetic correlations between age at initiation and amount smoked or smoking cessation were at most .22 in magnitude, indicating that genetic influences in age at initiation accounted for at most about 4% of the genetic factors in amount smoked or in cessation. Genetic factors are important in amount smoked and smoking cessation and they are largely independent of genetic influences on age at initiation. This has implications for defining phenotypes in searches for genes underlying smoking behaviors.
遗传因素和环境因素都会影响吸烟行为的开始和持续，但对于其他各种与吸烟相关行为的遗传结构，我们了解得较少。本研究的目的是在一个大型双胞胎队列中研究吸烟行为的遗传结构。我们向芬兰双胞胎队列中的同性成年双胞胎邮寄了包含详细吸烟史部分的问卷。最终的研究人群包括2923对同卵双胞胎和6018对异卵双胞胎，年龄在24至88岁之间。使用Mx统计软件包对开始吸烟年龄与吸烟量（每天少于20支香烟与20支或更多）以及开始吸烟年龄与戒烟情况进行了两阶段双变量遗传建模。对于男性，开始吸烟年龄的遗传度估计值为0.59（95%置信区间[CI]0.49 - 0.69），吸烟量的遗传度估计值为0.54（95%CI0.45 - 0.62），戒烟情况的遗传度估计值为0.58（95%CI0.50 - 0.65）。对于女性，遗传度估计值分别为0.36（95%CI0.28 - 0.43）、0.61（95%CI0.46 - 0.70）和0.50（95%CI0.39 - 0.60）。开始吸烟年龄与吸烟量或戒烟情况之间的遗传相关性最大为0.22，这表明开始吸烟年龄的遗传影响最多约占吸烟量或戒烟遗传因素的4%。遗传因素在吸烟量和戒烟方面很重要，并且在很大程度上独立于对开始吸烟年龄的遗传影响。这对于在寻找吸烟行为潜在基因时定义表型具有重要意义。
