Gene clues in asthma and Crohn's disease

Swedish scientists have identified two new genes linked to an increased risk of asthma and other breathing problems. Researchers at the Karolinska Institute say that alterations in the GPRA and AAA1 genes, located on chromosome seven, both make proteins involved in the disease. Their findings, published in the journal Science, could lead to new drug treatments for asthma. Meanwhile, Canadian scientists have identified a gene involved in Crohn's disease, an inflammatory bowel condition. Scientists at the University of Toronto, who published their results in the journal Nature Genetics, say the discovery is a step towards improved diagnosis and treatment of the disorder.

Asthma, which affects around 5.1 million people in the UK, is thought to be caused by the interaction of many genetic and non-genetic factors. Scientists have already identified several other genes involved in asthma, but the new Swedish study, which looked at DNA samples from nearly 900 people, is apparently the largest carried out so far. It seems that the two genes identified make a protein found in the cells lining the airways, and also in smooth muscle cells. Since asthma involves inflammation coupled with muscular constriction of the airways, the genes appear to play a direct role in the illness, claims study leader Juha Kere. 'This research is a culmination of a ten-year project to identify genes for complex diseases', he said.

Crohn's disease is also influenced by several different genes, and triggered by other, non-genetic factors. The new gene identified by the Canadian researchers makes a protein that sits on the cell surface, and regulates what enters and exits the cell. In people with Crohn's disease, this protein does not seem to work properly, allowing toxins to get into the cells more easily. 'Identifying this gene is a critical step towards improved diagnosis of this disease and developing better therapies for Crohn's sufferers', said study leader Katherine Siminovitch. However, she stressed that other genes were also involved, and that identifying them all would help identify 'potentially preventable environmental triggers'.