Is psoriasis hereditary?
The American Academy of Dermatology explain that if a parent, grandparent, or sibling has psoriasis, an individual has a higher chance of developing it. Scientists have also identified certain genetic factors that appear to play a role.
However, having a specific genetic feature or a family member with psoriasis does not mean that a person will necessarily develop the condition themselves.
Genetic changes can make psoriasis more likely to develop, but environmental triggers and changes in the immune system also seem to play a role. Without a specific environmental trigger, psoriasis may never develop — even in someone with psoriasis-related genetic features.
As researchers learn more about how genetic factors can impact psoriasis, people who have relatives with the condition can start to develop a better understanding of how likely it is to affect them.
Is psoriasis likely to be hereditary?
Studies show that psoriasis can run in families.
The reason that some people with the genetic features do not develop psoriasis is that:
- they may not have the right collection of genetic features
- they may not have had exposure to specific environmental triggers
This suggests that both environmental triggers and genes play a role in whether a person will develop psoriasis.
In other words, a person whose family members have psoriasis may have a higher chance of developing the condition themselves, but perhaps only if certain other factors are also present.
For this reason, it is not possible to predict who will develop psoriasis, and a person whose close relatives have psoriasis will not necessarily have it themselves.
How does psoriasis occur?
Psoriasis is a systemic condition that affects various body systems and involves a malfunction in the immune system.
The immune system exists to resolve problems that arise when harmful substances, such as infections or a virus, invade the body. Inflammation plays a role in this reaction. Sometimes, however, the immune system malfunctions and reacts to a threat that does not exist.
This reaction and the resulting inflammation can lead to damage in various parts of the body. In the case of psoriasis, it triggers an overgrowth of skin cells and other symptoms.
Skin changes are the hallmark sign of psoriasis, but inflammation can occur elsewhere in the body. If it happens in the joints, it can lead to psoriatic arthritis.
In most cases, genetic changes are not enough to activate psoriasis. An environmental factor will also need to be present to trigger the condition.
Possible triggers include:
- chronic infections
- low humidity
- the use of some medications, including beta-blockers and lithium
Excess alcohol consumption may also play a role in the development of psoriasis.
Conditions such as type 2 diabetes and cardiovascular disease are more likely to occur in people with psoriasis than those without it.
Learn more here about the triggers of psoriasis.
Which genes does it involve and how?
Scientists have identified various genetic factors that might underlie psoriatic disease.
Researchers have been investigating which genetic factors might make psoriasis more likely in some people. Different genetic changes may make specific types of psoriasis more likely.
Psoriasis-related genes mainly play a role in the immune system. According to the National Psoriasis Foundation, scientists have pinpointed around 25 genetic changes that may contribute to psoriasis.
We detail some of them in the sections below:
In 2012, researchers identified a mutation in a gene called CARD14 that appears to play a role in the development of psoriasis. Changes in this gene can result in additional inflammation, according to Genetics Home Reference.
Research suggests that the changes in CARD14 could lead to psoriasis when specific environmental triggers are also present.
Changes in other genes and gene groups may impact how the immune system works by increasing the inflammatory response.
Many genes may play a role in psoriasis or increase a person's susceptibility to the condition.
For example, the IL23R gene plays a role in the immune system pathway involving interleukins 17 and 23. Specific biologic therapies for psoriasis target these interleukins.
Changes in the human leukocyte antigen (HLA) complex may increase the risk of psoriatic arthritis. This gene group plays a role in distinguishing between foreign invaders and body tissue.
Each type of psoriasis may involve changes in a number of genes. In addition, some genetic changes may be present across various types of psoriasis. One gene can also have a range of variants.
Researchers are continuing to look into various genes and their connections with psoriasis.
How do scientists identify genes?
The process of determining which genes affect psoriasis is a difficult task involving the following steps:
- Researchers identify a genetic feature that is more common in people with psoriasis.
- They investigate how the gene functions in normal use.
- They look at how the gene behaves in a person with psoriasis, and how this behavior differs from its normal function.
How knowledge of genes can help
Ongoing research into genetic factors has led to more effective treatment options.
Researchers have so far determined the following points:
- Genetic factors increase a person's susceptibility to psoriasis.
- Some specific genes may play a role in psoriatic changes.
If scientists can find out exactly which genes cause a condition and how to change them, they may be able to develop novel treatments and even a cure.
Biologic therapy is now a common treatment option for certain types of psoriasis. These drugs target specific components of the immune system. They are effective at reducing the number of flares and the severity of symptoms.
Does chance play a role?
Researchers tend to agree that the most likely cause of psoriasis is that changes in specific immune-related genes combine with environmental triggers at a certain point in time.
Chance may play a minor role, since a person probably needs a very specific combination of genetic changes for psoriasis to develop. Even then, psoriasis may not occur without a trigger, such as an infection.
Some triggers are avoidable, but others are not. For example, people have vaccinations and practice good hygiene to reduce the risk of infection, but it is not possible to prevent all illnesses.
However, there is a higher incidence of smoking among people with psoriasis, which suggests that smoking may be a trigger for the condition. Smoking is one factor that people can choose to avoid.
If these factors are not in place, scientists believe that a person may not develop psoriasis in their lifetime.
There is evidence to suggest that psoriasis can run in families, and that genetic factors play a role. However, having a family member with psoriasis does not mean that a person will develop it themselves.
As researchers continue to learn more about the role of genes in psoriasis, new ways of treating and preventing the condition are emerging.
One day, this information might lead to a cure.