Genes and Psoriasis
Genes hold the key to understanding how the immune system becomes activated in people who have psoriasis and/or psoriatic arthritis. When a specific gene is found to be linked to psoriatic disease, researchers work to determine what the gene does under "normal" conditions. Next they try to determine how the gene is behaving differently in a person with psoriasis or psoriatic arthritis. This is a very difficult and time-consuming process, because researchers believe that more than one gene is responsible for causing psoriatic disease.
How do genes work?
Genes control everything from height to eye and hair color, by telling specific cells how to act. Differences between people result from having different versions of a particular gene. When genes are working normally, the body and its cells function normally. When a misstep occurs in the way a gene works, a genetic disease such as psoriasis may result.
How are genes different in people with psoriatic disease?
Researchers are investigating how the genes of people with psoriasis and psoriatic arthritis make them more likely than others to get these diseases. There are some possible genetic changes that could explain why psoriasis/psoriatic arthritis occurs. It is known that some people are more likely to have psoriasis than others, and this "susceptibility" may lie in the genes themselves.
Scientists have now identified about 25 genetic variants that make a person more likely to develop psoriatic disease. At the University of Michigan, Dr. J.T. Elder and his team of researchers have identified several areas on the human genome where more than one gene may be involved in psoriasis and psoriatic arthritis.
At the University of California-San Francisco, Dr. Wilson Liao is using new genetic sequencing technology to find rare "trigger genes" that may be the leading causes of psoriasis in certain individuals.
What does heredity have to do with it?
Scientists now believe that at least 10 percent of the general population inherits one or more of the genes that create a predisposition to psoriasis. However, only two percent to three percent of the population develops the disease.
This is thought to be because only two percent to three percent of people encounter the "right" mix of genetics and are exposed to triggers that lead to the development of psoriasis. Those who have a genetic disease but don’t have a family history of it, for example, may have inherited two genes from their father and two from their mother—neither of whom had all four and therefore never developed the disease.
Working with DNA samples from a large family that includes many people with psoriasis, Anne Bowcock, Ph.D., a professor of genetics at Washington University School of Medicine in St. Louis, has identified a gene mutation known as CARD14 that when activated with an environmental trigger leads to plaque psoriasis. Read more about Bowcock’s genetic discovery »
Are some genes linked to specific kinds of psoriasis?
At the University of Utah, Drs. Gerald Krueger and Kristina Callis Duffin have carefully catalogued the psoriasis of more than 1,200 patients. By comparing the genes of each individual to the way psoriasis shows up on his or her body, the team hopes to understand which genes are involved in specific types of disease.
Using a NPF Discovery grant, British researcher Francesca Capon found that a mutation to the gene called IL36RN might be involved in the three forms of pustular psoriasis.
What is happening with genetic research?
Research into the genetics of psoriasis didn’t begin until the early 1970s. Recently, it has exploded in scope, thanks to improvements in medical and genetic technology, and increased funding.
In 2006, the Foundation began collecting DNA samples for the National Psoriasis Victor Henschel BioBank. The BioBank is slated to be the world’s largest collection of psoriasis-related DNA in the world available to qualified researchers. The first BioBank DNA samples were released to researchers in 2010. Read about current studies using BioBank samples »
The predecessor to the BioBank was the National Psoriasis Tissue Bank. Launched in 1994, it was the first public source of genetic material for researchers investigating psoriasis. Just weeks after it opened, a research team from the University of Texas Southwestern and Baylor University Medical Center in Dallas announced the first genetic marker (a section of DNA that tracks with a disease) for psoriasis on chromosome 17.
What happens after the genes are found?
Discovering the genes that cause psoriasis will help identify the cause of the disease. Understanding the genetic component of psoriasis will go beyond showing that the immune system is activated, to telling us why it is activated and how that activation leads to defects in the skin. This will open the door to better control of psoriasis through more precise and effective treatments.
Once all the genetic factors causing the disease are found, researchers will be able to study why some people get psoriasis and others don't. By understanding how people who develop psoriasis are genetically different from people who do not, scientists may be able to create treatments that "correct" the behavior of cells. Or, they may be able to fix the differences in the genes themselves.
The treatment connection
Understanding the genes that trigger psoriasis in specific people and the pathways linking these genes to the immune system will someday improve treatment. Scientists may learn that certain treatments work better for people with a specific genetic variation. New treatments may be developed to interfere with the pathways that connect genes to the immune system.