Hong Kong University scientists are tracking the genetic cause of lower back pain, an affliction that affects almost everyone at least once. A single, mutated gene has been identified by overseas research in one-in-three sciatica patients, who experience the most severe type of back pain. The ailment, for which there is no cure, is caused when one or more discs between the vertebrae protrude under pressure in the lower spine, where the body's weight gathers. The discs press on the sciatic nerve, causing pain in the hips, buttocks and legs. The gene causes the premature degeneration of the cartilage discs, according to research in Finland published last year in the journal Science. Dr Kenneth Cheung Man-chee, an associate professor at Hong Kong University's department of orthopaedic surgery, said a better genetic understanding of the ailment could help develop a new gene therapy to reverse the discs' degeneration. 'There should be a genetic dimension in the formation of this physical disorder. This is highly probable on account of its prevalence,' he said. 'I expect the results to be slightly different from the Finnish study, mainly in terms of gene frequency, that would give rise to a different proportion of genetically related and unrelated cases. 'There are other genetic causes underlying the remaining two-thirds of lower back pain cases. We will go on to look for other gene defects.' The project, which is seeking a $2.5 million grant from the Area of Excellence Research Fund under the Research Grant Committee, began in August and is expected to be completed within three years.