Abstract: Objective To assess the genetic and environmental influences on lower extremity length index of middle childhood twins,and the effect of the age and sex. Method The quantitative genetic model-fitting and estimates of each index and genetic and environmental variance components were done with Mx software. Results The best fitting model of each index was ACES.After adjusting age,the heritabilities was as follows:height (male 43%,female 60%),sitting height (male 62%,female 62%),lower extremity length (male 50%,female 62%) and lower extremity length ratio (male 18%,female 36%).There were gender differences in heritabilities of height,lower extremity length and lower extremity length ratio. Conclusion Environmental factors play a leading role in the development of body length,which suggests that nutrition,physical exercises and controlling related diseases should be paid much attention to improve lower extremity length development to promote children's growth potential.

Key words: middle childhood, twins, lower extremity length, heritability

摘要： 目的 分析遗传与环境因素对童年中期双生子儿童下肢长相关指标的影响,并分析其中年龄和性别的作用。方法 对呼和浩特市和包头市5~8岁171对双生子儿童下肢长相关指标进行测量,使用Mx软件拟合最佳模型,计算校正年龄前后各指标遗传与环境方差组分。结果 各指标最佳拟合模型均为ACES,校正年龄后遗传度分别为:身高:男43%,女60%);坐高:男62%,女62%;下肢长:男50%,女62%;下肢长指数:男18%,女36%。身高、下肢长和下肢长指数的遗传度存在一定性别差异。结论 童年中期下肢长相关指标发育受环境因素的影响较大,应通过加强营养与锻炼及控制相关疾病等改善下肢长度发育,促使儿童生长发育潜力得到更好的发挥。

关键词: 童年中期, 双生子, 下肢长, 遗传度