Researchers have identified variants in the gene CHI3LI that are associated with increased susceptibility to asthma and reduced lung function. Checking levels of an inherited blood protein regulated by CHI3LI can measure the variants.
The blood protein, YKL-40, has recently been shown to be elevated in people with asthma and correlate with asthma severity. This new research shows that the YLKL-40 protein is inherited, and can be measured from birth.
"The investigators followed up on the discovery of a novel blood biomarker to identify a gene, which may have important implications in the early identification of susceptibility to, and prevention of asthma," says Elizabeth G. Nabel, MD, director of the National Heart, Lung, and Blood Institute.
The previous finding that the protein is a blood marker for asthma inspired researchers to look at the gene that regulates the protein. The relationship between the gene, the protein and asthma was first seen in a genetically and environmentally similar population of 700 members of an isolated religious community. The community has little exposure to smoking and similar exposures to environmental triggers for asthma. These factors make it easier to identify small differences in the genetic code.
Researchers then confirmed the connection between the gene and YKL-40 protein in three additional, more genetically diverse white groups in Chicago, Wisconsin, and Freiburg, Germany. Two of those populations confirmed the connection between the gene variants and asthma. One group, made up of 178 American children studied from birth, did not yet show a relationship between the gene and diagnosed asthma, but it did show that the associations between YKL-40 levels and the gene variants were present at birth.
"Knowing the variations in this one gene may help us learn more about how immune system development affects the risk of developing asthma," says Carole Ober, PhD, Department of Human Genetics, University of Chicago, and study author.
The National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health sponsored the study, which is published online in the New England Journal of Medicine.