The Basics – What Is a Gene?
You know that the CFTR is a gene – but what is a gene, exactly? The simple answer is that genes are the substance in our chromosomes that contain the code that tells our cells how to behave. For a deeper understanding of genetics, see this explanation of genes, DNA, and chromosomes.
What Is the CFTR Gene?
The CFTR gene, which is located on the seventh chromosome, is the section of DNA that is responsible for regulating salt and water movement between cells.
What Does the CFTR Gene Do?
CFTR is a transporter gene. The name of the gene literally explains what it does. Let’s break it down:
Cystic Fibrosis: The disease that occurs when the gene does not function properly
Transmembrane: The prefix “trans” means “across”, so transmembrane means “across the membrane”
Conductance: The ease with which electricity, gas, or fluid flows through a substance
Regulator: A mechanism of control
Gene: Provides instructions for creating a specific protein that the body needs to perform a particular function
Put that all back together and you know that the CFTR gene provides instructions for creating a protein that the body needs in order to control the ability of a substance to flow across some membrane. Specifically, the CFTR gene provides the information needed to transport sodium and chloride ions across the cell membrane. This in turn controls the flow of water in mucus, sweat, tears, saliva, and digestive enzymes.
What’s Different About the CFTR Gene in Someone With CF?
Cystic fibrosis occurs when the CFTR gene contains a mutation that prevents it from doing its job. There are about 1500 CFTR mutations in six different categories that are known to cause CF. Each category of mutation interferes with the CFTR gene in a different way, but the end result is the same. The mutation causes a change in the code, so sodium and chloride do not flow across the cell membrane properly and water does not get distributed as it should -- resulting in the thick, sticky mucus that causes problems in those with CF.
U.S. Department of Energy. CFTR: The Gene Associated with Cystic Fibrosis. 2008. The Human Genome Project. 01 November 2009.