SNPwatch: A Genetic Association with Knee Osteoarthritis

SNPwatch gives you the latest news about research linking various traits and conditions to individual genetic variations. These studies are exciting because they offer a glimpse into how genetics may affect our bodies and health; but in most cases, more work is needed before this research can provide information of value to individuals. For that reason it is important to remember that like all information we provide, the studies we describe in SNPwatch are for research and educational purposes only. SNPwatch is not intended to be a substitute for professional medical advice; you should always seek the advice of your physician or other appropriate healthcare professional with any questions you may have regarding diagnosis, cure, treatment or prevention of any disease or other medical condition.

gray345e.jpgNew research suggests that a genetic variation on chromosome 1 could be associated with increased risk of knee osteoarthritis among women.

The most common form of arthritis in the United States, osteoarthritis (OA) causes pain and inflammation in the joints and wears down protective cartilage. The Arthritis Foundation estimates that of the 27 million Americans afflicted with OA, 16 million of them are women who generally start feeling symptoms in their 40s.

To find out what genetic variants are most highly associated with knee osteoarthritis in women, Ana Valdes of the King’s College London School of Medicine and her colleagues combined information from a number of studies tracking women with knee OA over time in the U.S., U.K. and the Netherlands. The pooled genetic data from more than 1,500 knee OA patients and nearly twice that many controls were all from people of European ancestry over the age of 50 who suffered from regular bouts of morning stiffness prior to taking part in the study.

Valdes and her colleagues started small, first looking at the genomic data from 285 controls and 357 OA patients in the UK group. Then they compared the results with a UK replication cohort of 599 OA patients and 1,530 controls and a US group of 272 OA patients and 258 controls. Just as the regional auditions pare down contestants for the Hollywood phase of American Idol, the researchers used those studies to identify seven candidate SNPs, which were then analyzed in a group of 306 OA patients and 584 controls from the Netherlands.

In the end, all their data yielded one SNP linked to a 1.5-fold increased risk for knee OA in all five of the cohorts studied. The identified variant is the G version of rs4140564 on chromosome 1, a SNP that seems to have been association-free until now.

The researchers think rs4140564 may be co-inherited with the genes PTSG2 and PLA2G4A, which are located to either side of it on chromosome 1. Both genes are part of a pathway that could play a role in the bouts of inflammation thought to trigger OA. Describing their work in the current issue of The American Journal of Human Genetics, Valdes and her colleagues say more research is needed to confirm and understand the SNP’s relationship with the condition.
Image from Gray’s Anatomy, 20th ed.