Slemenda C W, Turner C H, Peacock M, Christian J C, Sorbel J, Hui S L, Johnston C C
Riley Hospital for Children, Indiana University School of Medicine, Indianapolis 46202, USA.
Osteoporos Int. 1996;6(2):178-82. doi: 10.1007/BF01623944.
To estimate genetic effects on femoral neck geometry and the distribution of bone mineral within the proximal femur a cross-sectional twin analysis was carried out at a university hospital that compared correlations in these traits in pairs of mono- and dizygotic female twins. Monozygotic (MZ, n = 51 pairs, age 49.1 +/- 9.3 years) and dizygotic (DZ, n = 26 pairs, age 45.7 +/- 11.3 years) twins were randomly selected from a larger sample of twins previously studied. Measurements of bone mineral density (BMD), femoral neck angles and length, cross-sectional area and moment of interia, the center of mass of the narrowest cross-section of the femoral neck, and BMDs of regions within the femoral neck were made. A summary index of the resistance of the femoral neck to forces experienced in a fall with impact on the greater trochanter (Fall Index, FI) was calculated. MZ pair intraclass correlations (rMZ) were significantly (p < 0.05) different from zero for all bone mass and femoral geometry variables (0.35 < rMZ < 0.82). DZ pair correlations (rDZ) were lower than rMZ for all variables (0.04 < rDZ < 0.52) except femoral neck length (rDZ = 0.38, rMZ = 0.36). After adjustment for BMD of the femoral neck, rMZ was significantly greater than rDZ, yielding high heritability estimates for regional BMDs (0.72 < H2 < 0.78), the center of mass of the femoral neck (H2 = 0.70, -0.04 to 1.43 95% CI) and the resistance of the femoral neck to forces experienced in a fall (FI, H2 = 0.94, 0.06 to 1.85 95% CI), but not for femoral neck length. Adjustments for age did not alter these findings. It is concluded that there are significant familial influences on the distribution of femoral bone mass and on the calculated structural strength of the proximal femur, but not on femoral neck length. If the assumptions of the twin model are correct, this is evidence for genetic factors influencing these traits.
为了评估遗传因素对股骨颈几何形状以及股骨近端骨矿物质分布的影响，在一家大学医院进行了一项横断面双胞胎分析，比较了单卵和双卵双胞胎女性在这些特征上的相关性。从之前研究的较大双胞胎样本中随机选取了单卵（MZ，n = 51对，年龄49.1±9.3岁）和双卵（DZ，n = 26对，年龄45.7±11.3岁）双胞胎。测量了骨矿物质密度（BMD）、股骨颈角度和长度、横截面积和惯性矩、股骨颈最窄横截面的质心以及股骨颈内各区域的BMD。计算了股骨颈在大转子受到撞击的跌倒中所承受力的阻力的综合指数（跌倒指数，FI）。所有骨量和股骨几何变量的MZ对组内相关性（rMZ）均显著（p < 0.05）不为零（0.35 < rMZ < 0.82）。除股骨颈长度外（rDZ = 0.38，rMZ = 0.36），所有变量的DZ对相关性（rDZ）均低于rMZ（0.04 < rDZ < 0.52）。在对股骨颈BMD进行调整后，rMZ显著大于rDZ，得出区域BMD（0.72 < H2 < 0.78）、股骨颈质心（H2 = 0.70，-0.04至1.43 95% CI）以及股骨颈在跌倒中承受力的阻力（FI，H2 = 0.94，0.06至1.85 95% CI）的高遗传度估计值，但股骨颈长度的遗传度估计值不高。对年龄进行调整并未改变这些结果。得出的结论是，家族因素对股骨骨量分布以及股骨近端计算得出的结构强度有显著影响，但对股骨颈长度没有影响。如果双胞胎模型的假设正确，这就是遗传因素影响这些特征的证据。
