Bouchard C, Simoneau J A, Lortie G, Boulay M R, Marcotte M, Thibault M C
Can J Physiol Pharmacol. 1986 Sep;64(9):1245-51. doi: 10.1139/y86-210.
The purpose of the study was to estimate the genetic effect for skeletal muscle characteristics using pairs of nontwin brothers (n = 32), dizygotic (DZ) twins (n = 26), and monozygotic (MZ) twins (n = 35). They were submitted to a needle biopsy of the vastus lateralis for the determination of fiber type distribution (I, IIa, IIb) and the following enzymes were assayed for maximal activity: creatine kinase, hexokinase, phosphofructokinase (PFK), lactate dehydrogenase, malate dehydrogenase, 3-hydroxyacyl CoA dehydrogenase, and oxoglutarate dehydrogenase (OGDH). For the percentage of type I fibers, intraclass correlations were 0.33 (p less than 0.05), 0.52 (p less than 0.01), and 0.55 (p less than 0.01) in brothers and DZ and MZ twins, respectively. MZ twins exhibited significant within-pair resemblance for all enzyme activities (0.30 less than or equal to r less than or equal to 0.68). In spite of these correlations, genetic analyses performed with the twin data alone indicated that there was no significant genetic effect for muscle fiber type I, IIa, and IIb distribution and fiber areas. Although there were significant correlations in MZ twins for all muscle enzyme activities, the often nonsignificant intraclass coefficients found in brothers and DZ twins suggest that variations in enzyme activities are highly related to common environmental conditions and nongenetic factors. However, genetic factors appear to be involved in the variation of regulatory enzymes of the glycolytic (PFK) and citric acid cycle (OGDH) pathways and in the variation of the oxidative to glycolytic activity ratio (PFK/OGDH ratio). Data show that these genetic effects reach only about 25-50% of the total phenotypic variation when data are adjusted for age and sex differences.
该研究的目的是利用非双胞胎兄弟（n = 32）、异卵双胞胎（DZ，n = 26）和同卵双胞胎（MZ，n = 35）来估计骨骼肌特征的遗传效应。他们接受了股外侧肌的针吸活检，以确定纤维类型分布（I型、IIa型、IIb型），并测定了以下酶的最大活性：肌酸激酶、己糖激酶、磷酸果糖激酶（PFK）、乳酸脱氢酶、苹果酸脱氢酶、3-羟酰基辅酶A脱氢酶和氧代戊二酸脱氢酶（OGDH）。对于I型纤维的百分比，兄弟、DZ双胞胎和MZ双胞胎的组内相关系数分别为0.33（p < 0.05）、0.52（p < 0.01）和0.55（p < 0.01）。MZ双胞胎在所有酶活性方面表现出显著的同对相似性（0.30 ≤ r ≤ 0.68）。尽管存在这些相关性，但仅用双胞胎数据进行的遗传分析表明，对于I型、IIa型和IIb型肌纤维分布及纤维面积，不存在显著的遗传效应。虽然MZ双胞胎在所有肌肉酶活性方面存在显著相关性，但在兄弟和DZ双胞胎中经常出现的不显著的组内系数表明，酶活性的变化与共同环境条件和非遗传因素高度相关。然而，遗传因素似乎参与了糖酵解途径（PFK）和柠檬酸循环途径（OGDH）的调节酶的变化以及氧化与糖酵解活性比值（PFK/OGDH比值）的变化。数据表明，在对年龄和性别差异进行校正后，这些遗传效应仅占总表型变异的约25% - 50%。
