Scientists have discovered a gene mutation that could up the risk of developing asthma by as much as 80 percent. A study of more than 2,000 children has pinpointed a single gene that may be at the core of the debilitating lung disease, which affects some 20 million Americans.
The gene, known as ORMDL3, is located on chromosome 17 (of the 23 chromosome pairs in the human genome); elevated levels of the protein for which it codes were found in the white blood cells of asthmatics.
The team reports in Nature that a single mutation in the script of nucleotides that form this gene may markedly increase a person's chances of developing the illness.
"The most strongly associated polymorphism [(variation in DNA)] increased the risk of asthma by 80 percent and potentially contributed to the disease in 30 percent of asthmatic children," says senior author William Cookson, professor of respiratory genetics at Imperial College London.
Cookson and colleagues compared the genetic profiles of 994 sufferers of childhood-onset asthma with those of 1,243 healthy children. They combed through more than 317,000 single-base mutations before they zeroed in on ORMDL3 as a possible risk factor. The genetic analysis was further bolstered by the hyperactivity of the gene in the blood cells of the asthmatics.
The researchers compared their genetic results with a sample of 2,000-plus children in Germany and a trial of 3,000 British subjects born in 1958. Many subjects in these studies showed flaws in the same section of the genome.
The function of ORMDL3 is unknown, Cookson says. But "similar genes are found as far back in evolution as yeast," he adds, "so it is part of an ancient mechanism and is presumably acting in innate immunity."
Even though the gene's role remains a mystery, researchers still believe it has therapeutic potential. "Its structure suggests that it may be a drug target," Cookson says. "We will now be investigating this possibility, but it will take a few years before any new treatments are likely."