Effect of Environmental Factors and Gender on the Heritability of Bone Mineral Density and Bone Size

Abstract

SummaryBone mineral density (BMD), a risk factor for osteoporosis, is believed to be under genetic control. The effect of environmental factors and gender on the heritability of BMD and bone size is ill-defined. In this study, heritability estimates (h 2 ) were determined in 3,320 southern Chinese subjects from 1,019 families using the variance components model. The h 2 for age, weight and height-adjusted BMD was 0.63-0.71 for females, and 0.74-0.79 for males; and for bone size, 0.44-0.64 for females and 0.32-0.86 for males. Adjustment for lifestyle factors including calcium and phytoestrogen intake, exercise, smoking and alcohol consumption altered the h 2 differently in males and females. The proportion of variance in BMD and bone size explained by all covariates varied between skeletal sites, but was consistently greater in females than males. A significant gender difference was observed in the genetic variance of BMD and bone size at the hip but not the spine. In conclusion, a gender difference was observed in the degree of heritability of BMD and bone size at specific skeletal sites. Environmental influences contributed variably at different sites in the two sexes.

Contribution of Gender‐Specific Genetic Factors to Osteoporosis Risk

“…We found that in females, percentage of variation explained by all the covariates was much higher than in males. Similarly, in a study of 3,320 Chinese subjects from 1,019 families (Ng et al, 2006), age, weight, height, as well as intake of isoflavones and calcium, physical activity, smoking, drinking, contributed from only 13% to 31% among men; for women, addition of age at menarche and menopause resulted in 32% to 46% of explained total variance in BMD. Similar results were reported in the Framingham families (R 2 from 8% to 20% in men but 19% to 41% in women (Karasik et al, 2002)) and in the Amish families (Brown et al, 2004).…”

Exercise and Bone Mass in Adults

“…In fact part of the effects described in the participants of different sports may have been caused by selection bias. Girls or boys with a larger musculoskeletal size and bone mass, [110] due to inherited characteristics, may choose to exercise because they may be more likely to be successful in competition and feel more rewarded by exercise practice. To rule out such a possibility, longitudinal studies and randomized clinical control trials are necessary.…”

Heritability of bone density: Regional and gender differences in monozygotic twins

“…6 Environmental factors also affect the risk for future fracture and include physical activity, calcium intake, smoking, and possibly alcohol intake. [6][7][8][9][10] While some studies have found site-specific gender differences in BMD heritability, others have observed no gender differences. 2 Many of these studies were limited in their site selection, often focusing mostly on BMD of the hip, spine, femoral neck and forearm, and only one 11 was a twin study.…”