Genes Play an Important Role in Bone Aging

Pathological changes in bones like osteoarthritis and osteoporosis are among the most frequent outcomes of age and aging. Presently, little is known about the genetic basis of peak bone mass or rate of bone loss, or on the genetics of bone formation and resorption. This paper reviews modern studies, dealing with the genetic aspects of bone formation and bone aging. The currently most popular measures of bone aging are: osteometric measurements (OSM) including measures of cortical thickness, bone mineral density (BMD), and osteographic scores (OSS) basing on descriptive criteria of bone age. These three are important clinical tools for predicting chronic degenerative disease and estimating biological age of individuals. Despite abundant data on ethnic and racial differences in these bone aging measures, modern knowledge regarding the genetics of the processes came primarily from family studies of BMD which point to strong familial and probably also genetic effects on bone mass. Regardless of the measurement technique or skeletal site selected, heritability estimates of BMD in most studies account for about 60% of the total variation in bone mass. Similarity of heritability estimates in most studies suggests that the same genetic factors operate on both weight-bearing and nonweight-bearing bones. However, genetic heritability may be overestimated in some family studies due to underestimation of common environmental effects. Segregation analysis, performed to date, reveals strong effect of potential major locus on BMD of both compact and trabecular bone, but much remains to be clarified. Genetic factors affecting BMD may be mediated through biochemical turnover of bone. Hence, segregation, linkage, and molecular biology are the staples of any genetic analysis of BMD, while the study of biochemical factors regulating bone turnover should elucidate the full picture of bone formation and aging.