Mutations and Classes

• In people with CF, mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause the CFTR protein to become dysfunctional. When the protein is not working correctly, it’s unable to help move chloride -- a component of salt -- to the cell surface. Without the chloride to attract water to the cell surface, the mucus in various organs becomes thick and sticky

• The defective CFTR gene contains an abnormality called a mutation. There are more than 1,700 known mutations of the disease. Most genetic tests only screen for the most common CF mutations. Therefore, the test results may indicate a person who is a carrier of the CF gene is not a carrier.

• Over the years, scientists have used several different ways of grouping these mutations into different classes. The most recent classification system groups mutations by the problems that they cause in the production of the CFTR protein:

The most common mutation, ΔF508, is a deletion (Δ signifying deletion) of three nucleotides that results in a loss of the amino acid phenylalanine (F) at the 508th position on the protein. The frequency distribution of genetic mutation causing the disease is:

*Source (This is our own internal analysis) sources are 

White papers written by doctors in various forums in NEJM etc

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2994562/

https://www.indianpediatrics.net/mar2014/185.pdf

https://www.indianpediatrics.net/sep2002/sep-813-818.htm

https://www.cysticfibrosisjournal.com/article/S1569-1993(07)00090-2/fulltext