GENETIC-VARIATION IN ALPHA-2HS-GLYCOPROTEIN IS RELATED TO CALCANEAL BROAD-BAND ULTRASOUND ATTENUATION IN OLDER WOMEN

Calcaneal broadband ultrasound attenuation (BUA) is an independent pre dictor of hip and vertebral fractures. BUA is under genetic control, b ut the specific genes contributing to BUA are not well defined. We exa mined the relationship between genetic variation in alpha(2)HS-glycopr otein (AHSG), an abundant noncollagenous protein of bone matrix, and c alcaneal BUA. Genetic polymorphism in AHSG was determined in 222 Cauca sian women (age 66-92) enrolled in the Pittsburgh Study of Osteoporoti c Fractures clinical center by isoelectric focusing of serum samples. Calcaneal BUA and bone mineral density (BMD) were measured on the same foot with a Walker Sonix UBA 575(+) and single X-ray absorptiometry. Hip and spine BMD were determined with a Hologic QDR-1000 densitometer using dual-energy X-ray absorptiometry. AHSG polymorphism was not sig nificantly related to hip, lumbar spine, or calcaneal BMD, Compared wi th the homozygous AHSG2 women, calcaneal BUA was 13% lower in heteroz ygous (P < 0.05) and 16% lower in homozygous AHSG1 women (P < 0.05). This relationship persisted after controlling for age, weight, height, walks for exercise, and calcaneal BMD. Current and self-reported heig ht were also lowest in homozygous AHSG1 women, intermediate in hetero zygous women, and highest among homozygous AHSG2 subjects. These resu lts suggest that the AHSG polymorphism may contribute to the genetic i nfluence on calcaneal BUA and stature.