VITAMIN-D-RECEPTOR GENE POLYMORPHISMS AND BONE-DENSITY IN PREPUBERTALAMERICAN GIRLS OF MEXICAN DESCENT

Background Bone mass is under strong genetic control, and recent studi es in adults have suggested that allelic differences in the gene for t he vitamin D receptor may account for inherited variability in bone ma ss. We studied the relations of the vitamin D-receptor genotype to ske letal development and variation in the size, volume, and density of bo ne in children. Methods We identified three allelic variants of the vi tamin D-receptor gene using the polymerase chain reaction and three re striction enzymes (Apal, Bsml, and Taql) in 100 normal prepubertal Ame rican girls of Mexican descent. We then determined the relations of th e different vitamin D-receptor genotypes (AA, Aa, aa, BE, Bb, bb, TT, Tt, and tt) to the cross-sectional area, cortical area, and cortical b one density of the femoral shaft and the cross-sectional area and dens ity of the lumbar vertebrae. Results The vitamin D-receptor genotype w as associated with femoral and vertebral bone density. Girls with aa a nd bb genotypes had 2 to 3 percent higher femoral bone density (P=0.00 8 and P=0.04, respectively) and 8 to 10 percent higher vertebral bone density (P=0.01 and P=0.03, respectively) than girls with AA and BE ge notypes. There was no association between the cross-sectional area of the vertebrae or the cross-sectional or cortical area of the femur and the vitamin D-receptor genotype. The chronologic age, bone age, heigh t, weight, body-surface area, and body-mass index did not differ signi ficantly among girls with different vitamin D-receptor genotypes. Conc lusions Vitamin D-receptor gene alleles predict the density of femoral and vertebral bone in prepubertal American girls of Mexican descent. (C) 1997, Massachusetts Medical Society.