Psoriatic arthritis (PsA) is an inflammatory condition that affects the joints and areas where the tendons and ligaments attach to bones. PsA affects all genders equally and typically develops after the age of 30. Studies suggest a genetic link to PsA.

PsA occurs when a person’s immune system is overactive and results in inflammation. A person may also experience pain and swelling in the joints or areas where the tendons and ligaments attach to bone.

Some people who develop PsA also have psoriasis, which is an autoimmune skin condition. People with psoriasis may have thick, scaly patches on their skin.

In this article, we examine whether PsA is genetic and how a person may inherit it. We will also discuss genetic testing for PsA and the early signs of the condition.

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Several factors cause PsA, including genetics and environmental factors.

PsA occurs in 20–30% of people with psoriasis. Research suggests a strong genetic link for PsA.

Some studies have identified genetic markers for PsA. A genetic marker is a sequence of DNA that has a precise physical location on a chromosome. Chromosomes are the protein structures that contain the genetic information needed to produce offspring.

Genetic markers may help track the heritability of specific genes or conditions. They may also help determine a person’s likelihood of developing a disease.

Some genes in the human leukocyte antigen (HLA) region could be associated with PsA. The HLA region is on the chromosome associated with immune function, and the HLA region is also associated with autoimmune diseases.

A 2021 systematic review found that two HLA region genes, known as HLA-B27 and HLA-B39, could be linked to PsA in psoriasis. The gene IL13 could also be associated with PsA.

Other genes that researchers have identified as having possible associations with PsA include:

  • HLA-B57
  • HLA-B38
  • HLA-C06
  • IL-23R
  • TNIP1

Between 33–50% of people with PsA have at least one close relative who also has psoriasis or PsA. However, the pattern of heritability is unknown.

A 2020 study found that PsA was a heritable condition, meaning that a parent can pass the condition through their genes to their children.

The study also notes that single nucleotide polymorphisms (SNPs) in the HLA region of chromosomes could be responsible for a significant proportion of PsA’s heritability.

SNPs are genetic variations in DNA nucleotides, which are the components that make up DNA. A person can inherit SNPs.

There is no single gene that can predict the presence or likelihood of developing PsA. A person may seek genetic testing for genes with moderate associations to PsA, such as HLA-B27. However, this would still not give any information regarding the likelihood of developing PsA or the severity of PsA.

A 2020 study investigated the performance of genetic testing in identifying PsA in people with psoriasis. The researchers note that genetic testing had a marginal effect on predicting a PsA diagnosis, despite the association of several PsA genetic markers.

There is no single test for PsA, according to the Arthritis Foundation. A doctor will use the following examinations, tests, and scans to confirm a PsA diagnosis:

Medical history

A doctor will typically begin by discussing symptoms and their severity. They may also examine the areas that are causing pain, such as the joints.

They may ask about a person’s family history, such as whether relatives have psoriasis or PsA.

Physical examination

A doctor may look for swollen and painful joints and patterns of arthritis and any skin or nail changes.

Tests

A person may need tests to confirm a diagnosis, including:

  • Imaging scans: X-rays look for joint damage or any changes to the bones or joints. Alternatively, a doctor may order an MRI, ultrasound, or CT scan.
  • Blood tests: Blood tests identify signs of inflammation. For example, the blood tests may look for C-reactive protein or rheumatoid factor (RF). A doctor may request blood tests to rule out other types of arthritis.
  • Fluid tests: A doctor may take a fluid sample from inside the joints to rule out other conditions, such as gout.

PsA may develop slowly, with mild symptoms appearing first, or progress very quickly and severely.

Early symptoms of PsA may include:

  • scaly, inflamed patches of skin
  • joint stiffness, pain, and swelling
  • tenderness in the areas where tendons and ligaments attach to bone, commonly the back of the heel or sole
  • painful swelling of the fingers or toes
  • crumbling, pitting, or separation of the nails from the fingers

A person should talk with their doctor if they notice any PsA symptoms. They should also contact a doctor if these symptoms become more severe very quickly.

PsA can lead to other health problems without treatment, and an early diagnosis is crucial in managing the condition. A person should see a doctor promptly if they experience PsA symptoms.

PsA is an inflammatory condition. It causes inflammation in the joints and areas where the tendons and ligaments attach to bones.

It results from an overactive immune system leading to inflammation. This can cause pain, swelling, and stiffness in a person’s joints and other symptoms such as swelling in the toes and fingers, nail and skin changes, and scaly patches of skin.

It is associated with arthritis, although a combination of genetics and environmental factors may also cause the condition.

There is a strong genetic association for PsA, with 33–50% of people with PsA having at least one other close relative with the condition. Genes such as HLA-B27 and IL13 have an association with PsA.

A person who experiences symptoms of PsA should see a doctor for a correct diagnosis.