Collagen type Iα1 gene polymorphism may be associated with the rate of bone mineral density decrease in female hemodialyzed patients

Background. Polymorphism of the collagen type Iα1 gene (COLIA1) has been shown to be involved in bone density in the general population. However, the significance of this polymorphism has not been examined in patients with chronic renal failure. Methods. We first determined the COLIA1 Bal I restriction fragment length polymorphism (RFLP) at the Sp 1 binding site, and, next, we measured biochemical bone markers and the bone mineral density (BMD) of the lumbar spine (L2-L4) and radius (distal one-third) in 181 hemodialyzed patients. Results. Distributions of the Bal I RFLP were: SS, 62%; Ss, 32%; and ss, 6%. The Z scores for the BMD and for the serum levels of Ca, P, alkaline phosphatase, intact-parathyroid hormone (PTH), osteocalcin, and tartrate-resistant acid phosphatase were not significantly different among the three genotype groups. The slope of the regression line in the age-BMD relationship, a measure of the rate of BMD decrease, was similar among the three genotypes in men, but was significantly (P < 0.05) larger in the ss group than in the SS and Ss groups in women. Conclusions. The COLIA1 polymorphism may be associated with the bone loss seen in female patients on hemodialysis.