Mutations in the CFTR gene result in cystic fibrosis in humans, a condition in which abnormal secretions are present in the lungs, pancreas, and sweat glands. The gene was mapped to a 500-kb region on chromosome 7 containing three candidate genes.

Using your knowledge of the disease symptoms, how would you distinguish between the candidate genes to decide which is most likely to encode the CFTR gene?

Key Concepts

Gene Function and Expression

Understanding gene function is crucial for identifying the CFTR gene. Genes encode proteins that perform specific functions in the body. The CFTR gene is responsible for producing the cystic fibrosis transmembrane conductance regulator protein, which regulates chloride ions across cell membranes. Analyzing the expression patterns of the candidate genes in tissues affected by cystic fibrosis can help determine which gene is likely to be CFTR.

Mutation Analysis

Mutations in the CFTR gene lead to cystic fibrosis, so analyzing the types of mutations present in the candidate genes is essential. This includes looking for known pathogenic mutations associated with cystic fibrosis. By comparing the mutation profiles of the candidate genes with those documented in cystic fibrosis patients, one can identify which gene is most likely to be the CFTR gene.

Phenotypic Correlation

Phenotypic correlation involves linking genetic information to observable traits or symptoms. In cystic fibrosis, symptoms such as lung infections and pancreatic insufficiency are key indicators. By examining which candidate gene's expression correlates with these symptoms in affected individuals, researchers can infer which gene is responsible for the disease, thereby narrowing down the candidates to the CFTR gene.