How does genetics influence risk, severity, and treatment of psoriasis?

8 minute read

What is psoriasis?

Psoriasis is a skin condition that causes red, flaky, and inflamed skin, often covered with silver-colored scales. In some people, symptoms can be relatively mild and affect a small amount of skin on the hands, elbows, or knees. In other people, symptoms can be severe and cover a large fraction of the body. About 30% of people also experience arthritis (pain/inflammation of the joints) but the reasons why some people do and some do not are largely unknown.

What is the main cause of psoriasis?

Psoriasis is an autoimmune condition. This means that the body’s immune system attacks and damages its own cells.

Autoimmune conditions like psoriasis are influenced by genetics, but not everyone who is predisposed will develop psoriasis. What triggers psoriasis in any given person can vary greatly. Autoimmune conditions like psoriasis are influenced by genetics In others, the caffeine in tea or coffee causes psoriasis rashes to occur.

One common question shortly after diagnosis is 'is psoriasis contagious’. As psoriasis is a result of the body’s immune system malfunctioning, there is no risk of passing the rash to a friend or partner.

What is the best treatment for psoriasis?

There are dozens of treatments, including both FDA-approved pharmaceuticals, over the counter remedies, and natural remedies for psoriasis.

For people with milder forms of psoriasis, moisturising cream can be used to treat psoriasis. Prescription creams such as Calcipotriene, which works by slowing down the growth of skin cells, are also effective for many people .

A number of pharmaceutical companies have developed treatments for psoriasis that are aimed at the root cause: the autoimmunity causing the body to attack it’s own skin cells. Many of these treatments are taken by mouth, or injected, and are most frequently prescribed for moderate or severe psoriasis.

Several of the most successful drugs include infliximab (Remicade), adalimumab (Humira), etanercept (Enbrel) - these drugs are a part of a new category of treatments called ‘biologics’ and have been very effective at treating psoriasis in many people. For some, the major symptoms of psoriasis go away permanently. However, for many people, especially those with more severe psoriasis, the existing treatments still do not work, or only treat part of the symptoms. For a given person, it is difficult to determine why a treatment does not work, but a growing body of evidence suggests that genetics plays an important role.

What role does genetics play?

Your genetics can influence your risk of developing psoriasis, severity, and even how your body responds to different treatments.

Research studies have shown, for example, that people carrying rs2395029 G/G are, on average, more than 4x more likely to develop psoriasis .

People carrying rs10484554 T/T are, on average, between 2x and 4x more likely to develop psoriasis. This genetic variant has also been shown to correlate with other autoimmune disorders such as Coeliac Disease and arthritis .

While these genetic variants cause a large increase in risk, there are hundreds of genetic variants which have been shown to associate with psoriasis risk. So, if you have psoriasis but do not carry any of the above genetic variants, you may carry some of the other risk-associated genetic variants. Of course, environment and diet also play a key role in addition to genetic susceptibility.

Beyond the risk of developing psoriasis, genetics can affect severity and response to treatment.

People carrying rs1799724 C/C or rs1061622 T/T genotype have been shown to respond better to Etanercept in initial studies .

We want to stress that these studies are very new, and the impact of genetics on treatment response in psoriasis is still in the research stage .

It is essential that you speak to a dermatologist before making any change to your treatment regimen based on research studies or genetic data.

Psoriasis and arthritis

About 1 in 3 people with psoriasis also experience psoriatic arthritis, inflammation of the joints caused by autoimmunity.

There is significant genetic overlap between psoriasis and psoriatic arthritis, but studies comparing the two have found genetic variants that can help predict the risk of developing arthritis.

For example, people that carry the rs34536443 G/G genotype are more than 2x more likely to have psoriatic arthritis.

The bottom line

Psoriasis and psoriatic arthritis are complex autoimmune conditions that affect 2-3% of people worldwide. Due to the wide range in severity and symptoms, what is the best treatment for psoriasis may depend on your genetics, your diet, and other health considerations. Being informed on the available treatment options, and discussing them with your dermatologist or rheumatologist is essential.

Image credit: Joel Filipe - Unsplash

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