Loos R J, Beunen G, Fagard R, Derom C, Vlietinck R
Faculty of Medicine, Department of Sport and Movement Sciences, Katholieke Universiteit, Leuven, Belgium.
Twin Res. 2001 Oct;4(5):356-64. doi: 10.1375/1369052012524.
An adverse intra-uterine environment has been associated with abdominal fat distribution in singletons. Twins often have a low birth weight and a short gestation. Therefore, they may have an increased risk to develop abdominal obesity. Furthermore, monozygotic monochorionic twins (MZ MC) have a larger intra-pair birth weight difference compared to monozygotic dichorionic twins (MZ DC). If adult anthropometry is programmed in utero, this may affect the intra-pair correlations in adulthood and, consequently, also the results from the classic twin method to estimate genetic and environmental influences. In the present study, we compared the absolute values, the intra-pair differences, and the intra-pair correlations of body mass, height, BMI, and abdominal fat distribution of 424 MZ MC, MZ DC and dizygotic (DZ) twin pairs (aged 18-34 yrs). DZ, MZ DC and MZ MC twins did not differ for most anthropometric characteristics. Only MZ women tended (p = 0.03) to accumulate more abdominal fat compared to DZ twins. Overall, the contribution of zygosity and chorion type to adult anthropometry was rather low (< or = 1.7%). Although the intra-pair birth weight difference of MZ MC pairs (10.5% in men, 12.3% in women) was significantly larger compared to that of MZ DC pairs (6.9% and 9.2% resp.), the intra-pair differences in adult anthropometry were similar for both MZ twin types. Also the intra-pair correlations of MZ MC and MZ DC pairs were strikingly alike, suggesting no significant influence of the prenatal environment on adult concordance. In conclusion, the substantial difference in the prenatal environment of MZ MC and MZ DC twins did not result in a difference in intra-pair concordance of adult anthropometry and fat distribution. Therefore, we suggest that the chorion type of MZ twins does not bias the twin design and the estimation of the genetic contribution to adult anthropometry.
子宫内不良环境与单胎的腹部脂肪分布有关。双胞胎通常出生体重低且妊娠期短。因此，他们患腹部肥胖的风险可能会增加。此外，与单卵双绒毛膜双胞胎（MZ DC）相比，单卵单绒毛膜双胞胎（MZ MC）的出生体重对内差异更大。如果成人人体测量指标是在子宫内编程的，这可能会影响成年后的对内相关性，从而也会影响经典双胞胎方法估计遗传和环境影响的结果。在本研究中，我们比较了424对MZ MC、MZ DC和双卵（DZ）双胞胎（年龄在18 - 34岁）的体重、身高、BMI和腹部脂肪分布的绝对值、对内差异和对内相关性。DZ、MZ DC和MZ MC双胞胎在大多数人体测量特征上没有差异。只有MZ女性与DZ双胞胎相比，往往（p = 0.03）积累更多的腹部脂肪。总体而言，合子性和绒毛膜类型对成人人体测量的贡献相当低（≤1.7%）。尽管MZ MC对的出生体重对内差异（男性为10.5%，女性为12.3%）明显大于MZ DC对（分别为6.9%和9.2%），但两种MZ双胞胎类型在成人人体测量方面的对内差异相似。MZ MC对和MZ DC对的对内相关性也非常相似，表明产前环境对成人一致性没有显著影响。总之，MZ MC和MZ DC双胞胎产前环境的显著差异并未导致成人人体测量和脂肪分布的对内一致性出现差异。因此，我们认为MZ双胞胎的绒毛膜类型不会使双胞胎设计产生偏差，也不会影响对成人人体测量遗传贡献的估计。
