Peutz-Jeghers syndrome is caused by alterations (mutations), at a specific area in a person’s genetic information. Each of us has a large amount of genetic information that is organized into smaller segments known as "genes." Genes provide the instructions that our cells need to perform different functions within our bodies.
There is a specific gene known as STK11 (also known as LKB1), located on chromosome 19 at position q13.3, that is altered in patients with Peutz-Jeghers syndrome. The STK11 gene has the ability to produce an enzyme called "serine/threonine kinase 11" that has several important functions:
It acts as a tumor suppressor - the enzyme keeps cells from growing and dividing too quickly and it promotes cell death.
It helps certain types of cells correctly orient themselves within tissues.
It helps determine the amount of energy a cell uses.
It is believed that through a combination of these mechanisms, STK11 aids in the prevention of tumors.