Cystic Fibrosis

A lot of diseases are caused by or associated with mutations in particular genes. One of these diseases is cystic fibrosis (CF), which causes severe lung and digestive system damage and leads to respiratory failure.

What Gene or Genes Are Related to Cystic Fibrosis?

1. Go to the OMIM database: http://www.omim.org/.

2. Search OMIM for "cystic fibrosis."

3. From the list of results, choose "219700. CYSTIC FIBROSIS; CF" in the search list. 

4. You will see a "Phenotype-Gene Relationships" table. The “Gene/Locus” column in this table tells you which gene is responsible for the phenotype, or the disease, as well as for any conditions related to the disease. The "TEXT" section below the table further clarifies the name of the gene that causes CF if it is mutated.

5. Write down the gene name that is associated with CF.

A researcher may also be interested in how or why mutations in genes cause diseases. To figure out how mutations affect a gene, it's important to know the normal function(s) of a gene.

What Is the Main Function of the Gene Associated with Cystic Fibrosis?

6. On the OMIM page for cystic fibrosis, look at the "External Links" box on the upper-right side of the page. Click the "Protein" -> “Uniprot” link, which takes you to the Universal Protein Resource (Uniprot) database for the gene that causes CF.

7. You should see a general description of the function of the protein encoded by that gene. 

8. What is this protein involved in? 

9. You should see a lot of other information on the Uniprot page, like “GO-Molecular function” and “GO-Biological process.” “GO” stands for “gene ontology.” Although many functions are listed in the “GO-Molecular function” section, they are closely related to each other. For example, the chloride channel activity depends on the ATP binding and ATPase activity because the protein needs the energy provided by ATP to transport the chloride ion.

10. Let’s summarize what you have learned from the OMIM and Uniprot databases.

• The Cystic Fibrosis Transmembrane conductance Regulator (CTFR) (CFTR) pumps Cl^- from the inside to the outside of the cell
• A mutation in the CFTR gene causes loss of the function.
• How does this relate to CF? If the mucous in the airway can’t get enough Cl^-, it will be severely dehydrated (resulting in much-thicker-than-normal mucus). The thick mucus will block the airway and trap bacteria, leading to infections and lung damage.

Additional Resources

More on cystic fibrosis

What is the Gene Ontology?