PTH gene variants do not predict hip fracture risk
MedWire News: Research suggests that parathyroid hormone (PTH) gene variants alter femoral neck geometry in elderly White women but do not significantly predict their risk for hip fracture.
Previously, haplotypes of the PTH gene, a regulator of calcium homeostasis, have been linked with fracture risk independent of bone mineral density (BMD), explain Fiona McGuigan (Lund University, Sweden) and co-workers.
To investigate the relationship between PTH haplotype and femoral neck bone size, the team examined 750 women aged 75 years or older participating in the Malmö Osteoporosis Prospective Risk Assessment study. In all, 117 of the women had experienced hip fracture after the age of 45 years.
The women were examined for six polymorphisms in the PTH gene that make up five common haplotypes 1, 2, 5, 8, and 9, and underwent dual energy X-ray absorptiometry to determine hip geometry.
As reported in the journal Calcified Tissue International, women with haplotype 9 had significantly lower hip geometry results than women with other haplotypes for cross-sectional moment of inertia, femoral neck width, and section modulus, after adjusting for height and weight. There was a dose-dependent effect between number of haplotype 9 copies and the geometry values.
Although these parameters indicate a potential for increased risk for hip fracture, women with haplotype 9 did not have a significantly increased rate of hip fracture than those with other haplotypes.
However, women with hip fracture had a significantly longer hip axis length (HAL) than those without hip fracture. HAL was not linked to any PTH haplotype, the researchers note.
“Polymorphisms in the PTH gene are associated with differences in aspects of femoral neck geometry in elderly women,” the team concludes. “However, the major predictor of hip fracture in our population was HAL, to which PTH gene variation does not contribute significantly.”
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By Lynda Williams