1. ¹Department of Molecular Biology, Institute of Gerontology, Nippon Medical School, 1-396 Kosugi-cho, Nakahara-ku, Kawasaki 211-8533, Japan
2. ²Tokyo Metropolitan Institute of Gerontology and Hospital, Tokyo, Japan
3. ³Department of Geriatrics, Faculty of Medicine, University of Tokyo, Tokyo, Japan

Correspondence: Mitsuru Emi, Department of Molecular Biology, Institute of Gerontology, Nippon Medical School, 1-396 Kosugi-cho, Nakahara-ku, Kawasaki 211-8533, Japan. Fax: +81-44-733-5192. E-mail: memi@nms.ac.jp.

Received 21 October 1998; Accepted 15 December 1998.

Abstract

Twin studies have shown strong correlations between bone mass and genetic factors. Some of the genes involved could regulate bone metabolism and bone formation and resorption, all processes that determine bone mass. One candidate gene, interleukin 6 (IL-6), has been implicated in the pathogenesis of bone loss because it stimulates osteoclasts. We investigated a possible association between the CA repeat polymorphism at the IL-6 gene locus and the bone mineral density (BMD) of radial bone in 472 postmenopausal Japanese women. Genotypes were classified into six groups according to the number of CA repeats present, from 13 to 18. BMD was expressed as adjusted BMD, which was the body mass index (BMI)- and age-adjusted average BMD. The 73 women who possessed an A1 allele (134 bp, containing 18 repeats of CA) had significantly lower adjusted BMD than those participants (n = 399) who did not carry an allele of that size (mean SD values, 0.294 0.064 vs 0.312 0.061 g/cm²; P = 0.0221). This result suggests that genetic variation at the IL-6 gene locus is associated with some determinants of BMD in postmenopausal women.