Schousboe K, Visscher P M, Henriksen J E, Hopper J L, Sørensen T I A, Kyvik K O
The Danish Twin Registry, Epidemiology, Institute of Public Health, University of Southern Denmark, Denmark.
Diabetologia. 2003 Sep;46(9):1276-83. doi: 10.1007/s00125-003-1165-x. Epub 2003 Jul 24.
AIMS/HYPOTHESIS: Family and twin studies have reported different estimates of the relative contribution of genetic and environmental factors to the quantitative traits glucose tolerance, insulin secretion, and insulin sensitivity. Our aims were to estimate these relative influences in a large sample of twins from the population and to assess the effect of age.
In this population-based, cross-sectional study we gave an oral glucose tolerance test to 317 women and 290 men who were same-sex healthy twin pairs between 18 to 67 years of age. The genetic, common environmental and individual environmental variance components for fasting and 120-min glucose and for fasting and 30-min insulin as well as the linear effects of age on these components were estimated by multivariate analysis (using the software FISHER).
In women and men the heritability for fasting glucose was 12 and 38%, for 120-min glucose it was 38 and 43%, for fasting insulin it was 54 and 37%, and for 30-min insulin it was 57 and 47%, respectively. Under the assumption of no non-additive genetic effects (no intra- or inter-gene interaction) there was no strong evidence for common environmental effects, barring significant effects for fasting glucose in women. Heritability decreased with age for 120-min glucose in women and fasting insulin in men, whereas it increased for 120-min glucose in men.
CONCLUSION/INTERPRETATION: This study indicates a limited additive genetic influence on the result of an OGTT, possibly with sex-specific age effects, and generally little or no influence of the common environment. Accordingly, there is a considerable individual environmental variation.
目的/假设：家庭和双胞胎研究报告了遗传和环境因素对糖耐量、胰岛素分泌和胰岛素敏感性等数量性状相对贡献的不同估计值。我们的目的是在来自该人群的大量双胞胎样本中估计这些相对影响，并评估年龄的作用。
在这项基于人群的横断面研究中，我们对317名女性和290名男性进行了口服葡萄糖耐量试验，这些受试者为年龄在18至67岁之间的同性健康双胞胎对。通过多变量分析（使用FISHER软件）估计空腹及120分钟血糖、空腹及30分钟胰岛素的遗传、共同环境和个体环境方差成分，以及年龄对这些成分的线性影响。
在女性和男性中，空腹血糖的遗传率分别为12%和38%，120分钟血糖的遗传率分别为38%和43%，空腹胰岛素的遗传率分别为54%和37%，30分钟胰岛素的遗传率分别为57%和47%。在不存在非加性遗传效应（基因内或基因间无相互作用）的假设下，除女性空腹血糖有显著影响外，没有强有力证据表明存在共同环境效应。女性120分钟血糖和男性空腹胰岛素的遗传率随年龄下降，而男性120分钟血糖的遗传率随年龄增加。
结论/解读：本研究表明，对口服葡萄糖耐量试验结果的加性遗传影响有限，可能存在性别特异性年龄效应，且共同环境的影响通常很小或不存在。因此，个体环境存在相当大的差异。
