Genetic basis of individual differences in tissue composition

Abstract

A total of 19 pairs of twin adolescent boys, 14 MZ and 5 DZ, were used to determine the relative contribution of the genotype to the individual differences observed in surface density of muscle, subcutaneous fat, and bone. The cross-sectional areas of these tissue components were calculated from photographs of the upper arm, taken by means of an ultrasonic apparatus. The respective mean percentage intrapair difference in MZ and DZ twins was 6.9 and 9.8 for total area, 6.6 and 7.8 for muscle, 13.9 and 32.0 for fat, and 6.7 and 31.3 for bone tissue. Interindividual variations in bone only could be ascribed to genetic differences.