A Twin Study Of The Bone Development Of Children And Adolescents

Objective: To investigate the heritabilities of skeletal age (SA) and maturity degree of hand and wrist bones of children and adolescents in different developmental stages. To understand the zygosity difference of female sexual development and the variation degree in some indexes when menarche occurred so as to pave the way for establishing the intervention measurements for the development of children and adolescents. Methods: 190 twins aged from 6 to 18 years were included in the study after informed consent. They were from the twin registry system established by Qingdao Municipal Center for Disease Control and Prevention. Zygosity diagnosis was performed by microsatellite polymorphism. SA was evaluated according to CHN scoring method through hand and wrist radiograph. Heritabilities of SA and maturity degree of hand and wrist bones were estimated by classic Holzinger equation. At the same time, the height and weight of twins were measured and the condition of menarche of female twins was also surveyed. The influences of heredity and environment on bone development and the relationship between bone development and female sexual development were analyzed by the comparison of within-pair difference and within-pair correlation coefficients between monozygotic twins (MZ) and dizygotic twins (DZ), and the analysis on the rate of coincidence and Kappa concordance within the twin pairs were performed. Results: 1. Bone development of children and adolescents was influenced by heredity. Within-pair SA difference of MZ was lower than that of DZ and within-pair correlation coefficients of MZ was higher than that of DZ in all subjects of each age group. The heritability of SA in all subjects is estimated as 0.777, in 6-7 age group 0.616, in 8-10 age group 0.805, in 11-13 age group 0.825, in 14-18 age group 0.874. The heritability of SA in all female and male subjects was 0.813 and 0.682 respectively, hi female infancy, child and adolescent twins, the heritability of SA was 0.322, 0.760 and 0.817 respectively. In male is 0.836, 0.658 and 0.817 respectively.2. The distal phalangeals were most likely to be influenced by genetic factors. The heritability of maturity degree of the distal phalangeals was 0.538~0.653. The capitateand hamate bone were more likely to be influenced by environment rather than by gene. The heritability was estimated as 0.365 and 0.439 respectively. The middle and proximal phalangeals were also less to be influenced by genetic factors.3. The coincidence rate of development level of hand and wrist bones in MZ was higher than that in DZ.4. The variation of SA is lesser than that of chronological age, weight and BMI. Conclusion: 1. Bone development is influenced by genetic factors. The influential degree on male is higher than that on female. Bone development in adolescence is most likely to be influenced by heredity.2. Menarche is influenced by heredity and SA can be used to predict Menarche.Postgraduate: DONG Li-yan(Nutrition and Food Hygiene) Directed by: Professor PANG Zeng-chang and ZHONG Jin-yi...