Peak bone mineral density at the hip is linked to chromosomes 14q and 15q

A major determinant of osteoporotic hip fracture is peak hip BMD which is a highly heritable trait. Caucasian American women have lower BMD and higher hip fracture rates than African American women. This study examines linkage of hip BMD in 570 Caucasian sister pairs and 204 African American sister pairs. It compares the results with our published study in a smaller overlapping sample of Caucasian sisters. Hip BMD was measured at neck, trochanter, Ward's, shaft, and total hip. Principal component analysis provided a novel BMD phenotype comprising neck and trochanter, common sites of fracture, and Ward's, site of lowest BMD. A 9 cM genome scan was performed for these phenotypes. Significant linkage was found at chromosomes 14q and 15q. At 14q, the 774 African American and Caucasian sister pairs together yielded the highest LOD score for trochanter (3.5) and at 15q the highest LOD score for femoral neck (4.3). This linkage study in Caucasian and African American healthy premenopausal sisters demonstrates that chromosomes 14q and 15q harbor genes that affect peak bone mass at the hip in women. Principal component had comparable LOD scores with those of the component phenotypes suggesting pleiotropic effects of these genes on hip phenotypes.