双生子学龄儿童体格发育遗传学分析

Genetic study on physical measurements in school-age twins

目的分析遗传与环境因素对学龄双生子儿童体格发育的影响,分析其中年龄和性别的作用。方法测量297对6~12岁（同卵167对,同性别异卵90对,异性别异卵40对）学龄儿童身高、坐高、体重、胸围、肱三头肌皮褶、肩胛下皮褶、髂前皮褶厚度;用Mx软件拟合最佳结构方程模型。结果各体格指标均与年龄相关,仅肱三头肌皮褶厚度与性别相关;各指标的遗传模型均为ACES,遗传方差组分高于环境方差组分,男性皮褶厚度的共同环境效应高于女性,皮褶厚度的年龄方差（0.02~0.17）明显低于其他指标（0.35~0.74）;校正年龄后,遗传度分别为身高（男0.80,女0.83）、坐高（男0.76,女0.79）、体重（男0.53,女0.73）、胸围（男0.72,女0.66）、肱三头肌皮褶（男0.51,女0.87）、肩胛下皮褶（男0.56,女0.86）、髂前皮褶（男0.51,女0.83）,女生体重及皮褶厚度的遗传度均明显高于男生。结论遗传因素对学龄儿童体格发育起主要作用,但年龄、性别对其也有一定影响。

Objective To analyze genetic and environmental influences on physical measurements of school-age twins,and the effects of sex and age.Methods A total of 297 twin pairs,including 167 monozygotic（MZ）,90 like-sex and 40 opposite-sex dizygotic（DZ） twin pairs,aged 6-12 years were investigated.The measurements inculded hight,sitting hight,weight,chest circumference,triceps skinfold,subscapular skinfold,and suprailiac skinfold.Model-fitting by Mx package was performed to evaluate the effects of heredity and environment.Results All of the physical measurements were related to age except triceps skinfolds was associated with age and sex.The genetic model for all items was ACES.Genetic variant component was higher than that of environment for each item.Common environmental effect on skinfolds in the boys was higher than that in the girls,and age variant components of skinfold（0.02-0.17） were lower than those of other items（0.35-0.74）.After adjusting for age,the heritabilities of hight,sitting hight,weight,chest circumference,triceps skinfold,subscapular skinfold,and suprailiac skinfold were 0.80,0.76,0.53,0.72,0.51,0.56,and 0.51 in the boys and 0.83,0.79,0.73,0.66,0.87,0.86,and 0.83 in the girls,respectively.The female＇s heritabilities of weight and skinfold were higher than those of the male＇s.Conclusion The body physical measurements of school-age children are mainly influenced by the genetic factors but the effects of the age and gender on the heritability should be considered too.