Breaking codes to broken bones

Boston University School of Medicine professor David Felson recently discovered eight sites on the human genome linking DNA to the development of osteoarthritis.

Also called degenerative joint disease, osteoarthritis is the most common form of arthritis and the leading cause of disability among adults. The disease is associated with the degeneration of protective cartilage, most frequently around joints in the hip, knee, hand and spine.

This degeneration causes bones to rub together, leading to swelling and pain in the joint and eventual loss of joint movement.

Felson’s research studied 793 elderly individuals with osteoarthritis in their hands and 684 of their middle-aged children. Felson said he and his colleagues in the Framingham Heart Study, a 54-year-old epidemiological study funded by the National Heart, Lung and Blood Institute of the National Institutes of Health and managed by Boston University, began the research in an effort to make a genetic connection between generations.

‘We looked to see if the disease in the hands was shared [between parents and children], which it was,’ Felson said. ‘We then looked to see if certain spots in [both parent and child] genomes appeared to harbor genes that would cause osteoarthritis and found that they did.’

This genetic link led Felson and his research team to suspect that sites on several chromosomes may be linked to an increased susceptibility to osteoarthritis. ‘Sites’ are DNA sequences that have served as landmarks on the developing map of the human genome.

‘We want to try to understand the genome that causes osteoarthritis so that we can identify individuals with an increased risk before they acquire the disease,’ Felson said. ‘These individuals can then alter the things that they do in order to decrease their risk.’

However, Felson said it remains unclear which genetic variations cause different forms of the disease and whether or not specific variations may lead to the development of osteoarthritis in specific joints.

‘There are a number of ways to find genes that might be likely to tell us where increased susceptibility lies,’ Felson said. ‘For example, there might be a gene for enzyme in cartilage that causes it.’

Felson said his research is still in its infancy, and many studies still need to be done in order to substantiate his findings involving the chromosome sites.

‘It’s still pretty early on in the process of finding genes. It will be a few years before we can really say that we’re secure in our understanding of what causes osteoarthritis,’ Felson said.