What Are Risk Factors For Developing Plaque Psoriasis?

Reviewed by: HU Medical Review Board | Last reviewed: July 2016.

Plaque psoriasis is a chronic skin condition that causes patches of skin to become thickened, inflamed, and scaly. Scientists are still working to understand what causes a person to develop this disease. While the exact cause of psoriasis is still unknown, there is a growing amount of evidence about some of the risk factors that can make a person more likely to develop the disease.1-3 These include:

Why is family history a risk factor for psoriasis?

Currently, family history of psoriasis is considered to be one of the most powerful risk factors that can make a person more likely to get psoriasis. A person has a family history of the condition if one or more of that person’s blood-related family members has or had psoriasis.

Family history is a major risk factor for developing psoriasis because scientists have gathered strong evidence that psoriasis has a genetic link. When a disease has a genetic link, it means that members of certain families are more likely to get the disease than members of families who do not. This is because of information that is contained in the many thousands of genes that are passed down from parents to their children. This genetic information controls every part of how a person’s body functions. Sometimes, the genes that are passed down through a family contain slightly different information (variations). Sometimes these variations have no effect, but in other cases, these variations can play a role in causing a person to develop many different types of diseases and conditions.

By studying many families that have a history of psoriasis, scientists have discovered 25 genes (so far) that can contain variations that they think are linked to the disease. If a child receives one or more of those genes from one (or both) parents, then that child is more likely to develop psoriasis at some point during their life than a child who did not receive those genes.

Around one-third of people who develop psoriasis have a parent, brother, or sister with the condition. Scientists estimate that a child will have about a 50% chance of getting psoriasis if both parents have it, and around a 10% chance if only one of the parents has the condition.

How does family history relate to other risk factors for plaque psoriasis?

It is important to understand that having a family history of psoriasis, or having any of those 25 genes that are linked to psoriasis, does not necessarily mean that you will develop psoriasis. Scientists believe that at least 10% of the population probably has the one or more of the genes linked to the condition, but only around 2%-3% of the population actually develops the disease.

While having a family history of psoriasis makes a person more likely to get the disease, it does not guarantee it. Similarly, having psoriasis does not mean that you will definitely pass it down to your own children. Scientists still do not exactly understand why some people with the gene variations related to psoriasis eventually develop the disease, while others do not.

However, they think that it is because psoriasis is caused by having a family history of the disease as well as being exposed to some other triggers or having other risk factors.

What are some other risk factors for psoriasis?

The more risk factors a person has for psoriasis, the more likely that person is to develop the disease. The symptoms of psoriasis are related to how the body’s immune system functions and having a viral or bacterial infection can weaken a person’s immune system, making certain people more likely to develop psoriasis. For example, people with HIV may be at a higher risk for psoriasis. Stress can also weaken a person’s immune system and make that person more likely to develop psoriasis.

Current and former smokers are more likely to develop psoriasis than people who have never smoked, making smoking a significant risk factor for psoriasis (as well as overall health) that should be avoided entirely. People who are overweight are also more likely to develop psoriasis than people who have a healthy body weight.

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