Collagen type I α1 Sp1 polymorphism, osteoporosis, and intervertebral disc degeneration in older men and women

Objectives: To examine whether collagen type I α1 (COLIA1) Sp1 polymorphism is associated with osteoporosis and/or intervertebral disc degeneration in older people. Methods: COLIA1 genotype was determined in 966 men and women (⩾65 years) of the Longitudinal Aging Study Amsterdam. The guanine (G) to thymidine (T) polymorphism in the first intron of the COLIA1 gene was detected by PCR and Msc I digestion. In the total sample, quantitative ultrasound (QUS) measurements, serum osteocalcin (OC), and urine deoxypyridinoline (DPD/Cr urine ) were assessed. A follow up of fractures was done every three months. In a subsample, total body bone mineral content (n = 485) and bone mineral density (BMD) of the hip and lumbar spine (n = 512) were measured by dual energy x ray absorptiometry (DXA). Prevalent vertebral deformities and intervertebral disc degeneration were identified on radiographs (n = 517). Results: People with the TT genotype had a higher risk of disc degeneration than those with the GG and GT genotypes (OR = 3.6; 95% CI 1.3 to 10). For men, higher levels of OC were found in those with the T allele than in those without it (GG v (GT+TT) 1.96 (0.06) nmol/l v 2.19 (0.09) nmol/l). COLIA1 polymorphism was not significantly associated with other measures of osteoporosis in either men or women. Conclusion: COLIA1 Sp1 polymorphism may be a genetic risk factor related to intervertebral disc degeneration in older people. Previously reported associations between the COLIAI Sp1 genotype and lower BMD or QUS values, higher levels of DPD/Cr, and an increased fracture risk in either men or women could not be confirmed.