EFFECT OF VITAMIN-D-RECEPTOR GENE ALLELES ON BONE LOSS IN EARLY RHEUMATOID-ARTHRITIS

Objective. Rheumatoid arthritis (RA) is a polygenic disease characteri zed by localized joint destruction and generalized osteoporosis result ing in increased fracture risk, The pathogenetic mechanisms that deter mine the severity of generalized bone loss in RA are poorly understood . Polymorphisms in the vitamin D receptor (VDR) gene have been describ ed as a significant determinant of bone turnover and mass. In this pro spective study we describe VDR gene allele effects on bone loss in pat ients with early RA. Methods. We recruited 232 patients with early RA, Bone mineral density measurements were repeated in 167 patients. Seri al clinical and laboratory measures were recorded during the period of followup. DNA extraction, polymerase chain reaction amplification, an d restriction fragment length polymorphism analysis of VDR alleles wer e performed using standard techniques, Presence of the Tag restriction site for both alleles was denoted ''tt'', and absence ''TT''. Results . In women with RA the tt genotype group lost bone more rapidly than s ubjects with TT genotype at both the lumbar spine (-0.1 vs 4.9% p.a. r espectively; p < 0.05) and femoral neck (-3.9 vs -9.69%, respectively; p < 0.01). The effect was independent of other disease characteristic s. Conclusion, The presence of the VDR gene ''t'' allele in female pat ients with RE was associated with accelerated bone loss.