Canadian researchers have discovered a genetic variant that can increase the severity of lung deterioration in children with cystic fibrosis.

Cystic fibrosis is a fatal genetic disease that predominantly affects the lungs and the digestive system. It is usually diagnosed in the first year of life, according to the Canadian Cystic Fibrosis Foundation.

Scientists at the Hospital for Sick Children, the University of British Columbia, the University of Toronto and Université de Montréal have identified a gene variant that makes CF patients more prone to a bacterial infection that can cause a rapid decline in their lung function.

The presence of the variant of the TGFB1 gene means the body produces less MBL2, a protein that defends us against bacterial infection. Almost all CF patients are prone to a type of bacteria called Pseudomonas aeruginosa, which causes lung disease. But in those patients where MBL2 levels are very low, the infection can set in sooner, leading to a chronic infection and a resistance to antibiotics.

"The study shows that those exhibiting this genetic combination may be at a higher risk of acquiring this infection at a younger age — on average nearly five years earlier than those with gene variants that produce normal MBL2 and TGFB1 levels — most likely leading to a faster rate of decline of pulmonary function," said Dr. Julian Zielenski, an associate scientist in the genetics and genome biology program at the Hospital for Sick Children and a lead author of the study.

"Patients experience a vicious cycle of infection and inflammation that destroys lung tissue, inhibits lung function, and erodes quality of life."

The researchers hope to one day develop a genetic test that can predict the severity of a patient's lung disease and possibly lead to MBL2 supplements.

In the study, researchers compared the MBL2 and TGFB1 genotypes of 1,019 children with CF. The findings are published in the February issue of the Journal of Clinical Investigation.