Is psoriatic arthritis genetic?

When faced with a psoriatic arthritis diagnosis, one of the many questions that may arise in your mind is: Can this happen to your child? Or your brother or sister? In other words, does the condition run in your family?

It’s possible, actually: There’s a genetic component to PsA—about 40 percent of people with psoriatic arthritis have an inherited connection to the condition, according to the National Library of Medicine.

Psoriatic arthritis, also called PsA, is an autoimmune condition that causes inflammation in the joints and often (though not always) leads to red, scaly patches on the skin, swollen fingers and toes, nail changes, and back pain. back, among other symptoms, according to the American College of Rheumatology.

With PsA, your immune system overreacts and turns against your body, triggering an inflammatory response that leads to the above symptoms, according to the National Institute of Arthritis, Musculoskeletal and Skin Diseases (NIAMS).

There are two factors, NIAMS says, that play a role in the immune response that leads to psoriatic arthritis: your genes and your environment. Nature and nurture, if you will, and they’re important to keep in mind when considering the question Is psoriatic arthritis genetic? We reached out to some experts for their take on PsA and genetics.

Genes associated with psoriatic arthritis

First, a quick reminder of what genes are: Genes, which are passed down from your parents, are like little codes inside your body that tell you how to grow and function. They’re made of DNA, a long string of nucleotides, molecules that combine to create instructions for your body to follow. Each gene has a specific job, such as determining eye color or height. Your cells read genes and use them to make proteins, which are like workers that perform different tasks in your body. There are several genes that have been linked to psoriatic arthritis, including:

HLA complex (human leukocyte antigen)

According to the National Library of Medicine, this is the best-known group of genes that play an important role in the immune system’s ability to recognize and respond to foreign invaders. HLA also helps the body recognize its own harmless proteins. If the immune system shorts out while making this call, it could attack itself, which is what happens in autoimmune conditions like psoriatic arthritis.

According to a study published in The Journal of Rheumatology, there are about 20 genetic variants that can be linked to psoriatic arthritis. In addition to HLA complex genes, this includes:

  • IL-12B

  • IL-23R

  • IL-23A

  • TNIP1

  • TRAF31P2

  • CSF2/P4HA2

  • HCP5

  • FXL19

  • REL

  • TYK2

  • NOS2

  • PTPN22

  • TNFAIP3

  • IFNLR1

  • IFIH1

  • NFKBIA extension

Although these genetic variations play a role in immune function and response, according to the National Library of Medicine, they are thought to play only a small role in overall psoriatic arthritis risk. In other words, if you have one of these genetic mutations you are not automatically doomed to get psoriatic arthritis.

What is the link between psoriatic arthritis and genetics?

Despite that long list of genetic variants, the link between genetics and PsA isn’t strong enough to take that information and use it in any way. Overall, there is no gene that makes you more likely to develop psoriatic arthritis than if you didn’t have that gene, says Anca Askanase, MD, rheumatologist and professor of medicine at Columbia University Vagelos College of Physicians and Surgeons in New York . City. It means that scientists can’t pinpoint one gene to say it causes PsA. There are too many places in the immune system where things can go wrong and trigger disease, she explains.

Additionally, a family history of psoriatic arthritis can make you more susceptible to the condition, but genetics alone aren’t enough to trigger psoriatic arthritis, says Eric Ruderman, MD, a rheumatologist at Northwestern Medicine in Chicago. It’s a two-shot process, he says. Genetics may give you a predisposition to develop it, but you need something else in the environment that triggers the condition. As NIAMS points out, environmental triggers are the second part of the process and can include obesity, infection, injury and stress.

Are genetic tests available for psoriatic arthritis?

If you have psoriatic arthritis, you may be wondering if there is a way to screen your children for the condition. But there are no currently available genetic tests for PsA. While we know there is a familial association, the genetic component of psoriatic arthritis isn’t quite ready for prime time, says Dr. Ruderman.

In essence, this means that even though the medical community recognizes the existence of genetic risk factors for PsA, science has not yet evolved to where specific genes are tested and the results are used to inform treatment decisions. So you can’t have your children tested for certain genes and then take certain steps to prevent or treat them before the disease develops.

This is totally different from, say, breast cancer. BRCA gene mutations can be inherited from one or both parents; if you have any, you have a higher risk of developing breast, ovarian and other cancers, notes the National Cancer Institute. We don’t have a BRCA for psoriatic arthritis—if we do, we marry people and inform those diagnosed with psoriatic arthritis that their children may need to be tested as well, explains Dr. Askanase. When it comes to psoriatic arthritis, the research available today doesn’t provide enough evidence to suggest that anyone is being genetically tested.

However, it is true that psoriatic arthritis tends to run in families (again, four out of 10 people living with PsA have a family history of PsA or psoriasis), particularly first-degree relatives, which include children, parents and brothers. You share more of your DNA with these people than with other relatives. That said, there is less correlation between second-degree family members, such as aunts/uncles, grandparents, nieces, and half-siblings.

Additionally, Dr. Ruderman points out, inflammatory bowel disease (IBD), such as Crohn’s, or ankylosing spondylitis are two autoimmune conditions that appear to fall in the same genetic bucket as PsA. If you or a family member has any of these conditions, it suggests you may have genes associated with this group of diseases.

How psoriatic arthritis is diagnosed and treated

If you have a relative or have been diagnosed with psoriatic arthritis or a related chronic condition, such as IBD, it makes sense to have PsA on your radar, says Dr. Askanase. If you begin to notice symptoms, such as stiff or uncomfortable joints or red, itchy, scaly plaques of skin (no matter how small), talk to your doctor and explain your family history. These problems can be attributed to other things, but it’s always good to get checked first rather than wait.

Understanding that autoimmune rheumatic diseases, such as psoriatic arthritis, run in families is crucial. People need to be alert if their family member has any of these conditions, says Dr. Askanase. (Of course, not everyone is forthcoming about their medical history, and that’s okay.)

Diagnosis

There is no single test that can diagnose PsA. Your doctor will perform a physical exam and check your skin for signs of psoriasis. They may also do lab tests to rule out other causes of joint pain such as rheumatoid arthritis or gout. These include:

  • Blood analysis. If you test positive for rheumatoid factor (RF), you probably don’t have PsA; most people with PsA are almost always RF negative. Your doctor will also check your levels of C-reactive protein (CRP), which is a protein made by the liver that increases with inflammation.

  • Joint fluid test. Drawing fluid from an inflamed joint can help your doctor rule out gout. If the test indicates that you have high uric acid, gout could be the reason.

  • X-ray. These images can be helpful in diagnosing psoriatic arthritis if the disease has been present for a long time but not diagnosed. An x-ray can reveal what type of damage has occurred and whether the bones are changing shape.

  • Magnetic resonance imaging (MRI). An MRI scan can provide a detailed picture of both hard and soft tissue, making it particularly effective for pinpointing inflammation around tendons and identifying early signs of PsA that an X-ray can’t detect.

Treatment

Treatment for psoriatic arthritis depends on the severity of your symptoms and the extent of joint damage. It can range from anti-inflammatory drugs, disease-modifying antirheumatic drugs (DMARDS), and biologics. Other lifestyle adjustments such as physical therapy, weight loss and topical skin treatments can help skin symptoms and improve mobility and physical function, says the Johns Hopkins Arthritis Center.

There’s one bright spot when it comes to genetics and PsA: In the future, genes could provide the pathway to precision medicine. We’re slowly getting to the point where one of the ways to decide between six or eight treatment options might be genetics, says Dr. Ruderman, noting that, right now, choosing a drug is largely based on trial and error. This can be frustrating and extremely costly. There’s the promise that genetics can help us get on the right track, but it’s still early days and we don’t have those answers, he says.

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