Q89R polymorphism in the LDL receptor-related protein 5 gene is associated with spinal osteoarthritis in postmenopausal Japanese women

Study Design. An association study investigating the genetic etiology for spinal osteoarthritis. Objective. To determine the association of single-nucleotide polymorphism (SNP) causing an amino-acid change (Q89R) in the low-density lipoprotein receptor-related protein 5 (LRP5) coding region with spinal osteoarthritis. Summary of Background Data. Wnt/beta-catenin signaling pathway regulates bone density through a Wnt coreceptor LRP5. This pathway is also involved in cartilage development and homeostasis, suggesting that genetic variation in LRP5 gene may affect the pathogenesis of cartilage-related diseases, such as osteoarthritis. Methods. We evaluated the presence of osteophytes, endplate sclerosis, and narrowing of disc spaces in 357 Japanese postmenopausal women. Missense coding SNP for Q89R of LRP5 gene was determined using Taq-Man polymerase chain reaction (PCR) method. Results. We found that subjects without the R allele (QQ; n = 321) had a significantly lower osteophyte formation score than did subjects bearing at least one R allele (QR + RR; n = 36) (7.80 vs. 10.89, P = 0.0019 by analysis of covariance). Conclusions. We suggest that a genetic variation at the LRP5 gene locus is associated with spinal osteoarthritis, in line with the involvement of the LRP5 gene in the bone and cartilage metabolism.