Some people with cystic fibrosis have a very severe form of the disease, while others have ‘milder’ symptoms. Such variations are a result of over 1,700 mutations in the gene responsible for CF and environmental factors, as well as modifier genes – genes that do not cause cystic fibrosis but influence its severity.
So far, scientists have identified modifier genes of cystic fibrosis that affect the age of the first onset of Pseudomonas aeruginosa infection, severity of lung disease, presence of CF-related liver disease, and presence of meconium ileus (an intestinal blockage) at birth.
Several Cystic Fibrosis Canada-funded researchers are investigating modifier genes. Collectively, this research may help develop personalized treatments based on a more complete genetic profile.

Dr. Christina Haston (McGill University, Montreal) is searching for modifier genes that influence immune response in the lungs of CF mice. Her findings may help develop therapies targeting an individual’s immune system, reducing the severity of CF lung disease over time.

Dr. Andrew Sandford (The University of British Colombia, Vancouver) is analyzing the genetic information of people with cystic fibrosis and their families to identify modifier genes that affect the severity of CF.

Dr. Julian Zielenski (The Hospital for Sick Children, Toronto) is analyzing genetic information obtained from the cystic fibrosis population to identify modifier genes influencing CF disease progression.

Dr. Lisa Strug (The Hospital for Sick Children) is analyzing data on the Canadian CF population, such as nutritional status, to identify indicators of disease severity. This information will then be linked with genetic data to help identify modifier genes and their effects on disease severity.
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Reviewed/updated: 2011-01-31