HARROGATE, ENGLAND — To better understand the genetic components of osteoporosis, a University of Edinburgh researcher is planning to study the relationship between the two in the isolated population of the Orkney Islands.
Dr. Stuart Ralston, professor of rheumatology and head of the school of molecular and clinical medicine at University of Edinburgh, said research has shown that bone mineral density (BMD) in osteoporosis patients is almost certainly regulated by genetic signals.
Genetic factors explain 60%–85% of the variance in BMD, including type I collagen affecting bone structure, vitamin D receptors affecting mineralization, estrogen receptors affecting hormone action, and interleukin-1 and interleukin −6 affecting inflammation. However, the effects of individual genes appear to be small and may be magnified only by the interactions of multiple genes.
Orkney—an archipelago of 70 or so islands about 10 miles off the northern tip of Scotland—is one of the more isolated regions of Europe, and it has good genealogical records, making it possible for researchers to get a clearer picture of the way genetics affects bone health, Dr. Ralston said.
Dr. Ralston said colleagues were already planning to test the Orkney Islands population for genetic factors related to cardiovascular disease, so he asked them to tack on the factors for osteoporosis as well.
“Linking studies conducted in general isolated populations are good,” Dr. Ralston said June 26 during a workshop at the annual conference of the National Osteoporosis Society.
“If you're going to study osteoporosis or any other complex disease, I would study an isolated population because you're more likely to find something,” Dr. Ralston said.
One study of the Icelandic population showed that a variation in the gene BMP2 in chromosome 20 was correlated to osteoporosis. That study found that variation was present in 5% of people with low BMD at spine or hip or a fracture, compared with 1% in the control population.
Dr Ralston said he confirmed that work with an isolated population in northeast Scotland, where 3% of fracture patients had that same variation, compared with 0.04% of the control population.
“It's still rare,” Dr. Ralston explained. “One of the advantages of studying an isolated population is that you're more likely to discover a gene. One of the disadvantages of this is, is it applicable for the rest of the world?”
The study will go beyond the BMP2 gene to include the entire human genome for correlations to osteoporosis. But even with research into the genetic components of osteoporosis, identifying a single marker that will help physicians identify likely hip fracture patients may be impossible, he said.