Genetics study on circumference in preschool-age twins

【Objective】 To assess the genetic and environmental influences on body circumference of preschool-age children,and the effect of sex and age.【Methods】 A total of 101 twin pairs aged 3~6 years old were measured,including 42 monozygotic(MZ),30 like-sex and 29 opposite-sex dizygotic(DZ).The circumference items included head circumference,chest circumference,waist circumference,hip circumference,arm circumference and calf circumference.The structural equation modeling was used to evaluate the heritability of each circumference item.【Results】 Except head circumference's fitting model was AES,others were ACES,which indicated that the circumference items were influenced by genetic,environmental factors and age effects.After adjusting age,the heritabilities of head circumference,chest circumference,waist circumference,hip circumference,arm circumference and calf circumference were 0.83,0.56,0.77,0.49,0.58,0.82 in boys,and 0.75,0.43,0.72,0.63,0.36,0.76 in girls respectively.【Conclusion】 The circumference of head,waist and calf of preschool-age children are mainly influenced by genetic factors,the circumferences of chest,hip and arm are mainly influenced on environmental ones.