Genetic Marker for Rheumatoid Arthritis
Rheumatoid arthritis is known to have four genetic markers.

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by pain, stiffness, swelling, limited mobility, and loss of joint function. 

Scientific evidence suggests that genes and family history can predispose an individual to the risk of RA. However, environmental factors such as age, gender, and smoking also play an essential role in triggering the condition.

What are the genetic markers associated with RA?

Four known genetic markers associated with rheumatoid arthritis (RA) include:

  1. Human leukocyte antigens: The most common and significant genetic mutation associated with RA.
  2. Signal transducer and activator of transcription 4: Responsible for the regulation and activation of the immune system.
  3. Tumor necrosis factor receptor-associated factors: Have a major role in chronic inflammation.
  4. Protein tyrosine phosphatase 22 genes: Influence the progression and expression of RA.

What is rheumatoid arthritis?

Rheumatoid arthritis (RA) is a chronic, inflammatory disease in which the immune system mistakenly attacks the lining of the membrane, which surrounds joints, particularly the smaller joints of the hand and wrist, although larger joints such as the shoulders, hips, and knees may become involved later in the disease.

RA is estimated to affect up to one percent of the population worldwide.

Most joints are covered with a lining called the synovium that lubricates the joint for easy movement.

In RA, the synovium becomes inflamed (synovitis), thickens, and produces an excess of joint fluid. This fluid along with the inflammatory chemicals released by the immune system causes swelling, damages cartilage, and softens the bone within the joint. 

The swollen tissues stretch the surrounding ligaments, resulting in deformity, instability, and weakened and damaged tendons and ligaments.

What causes rheumatoid arthritis?

Although the exact cause of rheumatoid arthritis (RA) is unknown, researchers speculate a combination of genetic, hormonal, and environmental factors may play a key role in the development of RA. Infection, smoking, or physical or emotional stress may also act as triggering factors.

Immune factor

  • RA is an autoimmune disorder that occurs when the immune system attacks the body's tissues and organs.
  • The immune system triggers abnormal inflammation in the synovium, causing pain, swelling, and stiffness in the joint. 
  • In severe cases, the inflammation can affect the bone, cartilage, and other tissues within the joint, causing serious damage. 

Genetics

  • The most significant genetic risk factor for RA is variations in human leukocyte antigen (HLA) genes, especially the HLA-DRB1 gene.
  • The proteins produced from HLA genes help the immune system distinguish the body's proteins from proteins made by foreign invaders (viruses and bacteria). 

Environmental factors

  • Although the mechanism is unclear, certain factors that may trigger the condition in people who are at risk include changes in sex hormones (especially in women), occupational exposure to dust or fibers, viral, or bacterial infections, and long-term smoking.

What are the risk factors for rheumatoid arthritis?

Although rheumatoid arthritis (RA) can affect anyone, certain factors can make you more vulnerable to developing the condition, including:

  • Age (People older than 40 years are more prone to develop RA.)
  • Gender (Women are two to three times more likely than men to develop RA.)
  • Obesity
  • A family history of RA
  • Smoking (especially for people with the genetic marker, HLA-DR4)
  • Certain hereditary conditions (congenital malformed joints)
  • Activities and jobs that put high stress on the joints

RA typically presents signs and symptoms in late adulthood although it can develop at any age.

People affected with RA may have flare-ups (episodes of symptoms) followed by remissions (periods with no symptoms) for the rest of their lives.

The most common signs and symptoms include:

  • Pain, swelling, and stiffness of the joints
  • Symmetric arthritis (joints are typically affected in a symmetrical pattern; both hands and feet are affected simultaneously)
  • Joint pain and stiffness worsen in the morning or after a long period of rest

RA can also cause inflammation of other tissues and organs such as the eyes, lungs, and blood vessels.

Additional symptoms may include:

QUESTION

The term arthritis refers to stiffness in the joints. See Answer

How is rheumatoid arthritis diagnosed?

Unfortunately, there is no single test to diagnose rheumatoid arthritis (RA) in its early stages.

A healthcare provider will examine the affected joint and may recommend certain tests:

  • Blood tests: To check for
  • Physical examination: To look for
    • Noticeable swelling
    • Redness and warmth
    • Reduced range of motion
    • Pain
    • Joint instability
  • Imaging techniques: An X-ray of the affected joint may show
    • Bone spurs
    • Worn-down cartilage
    • Loss of joint space
  • Other tests: An MRI or a CT scan may be required to determine the condition of the bone and soft tissues of the affected joint.

What are the complications of rheumatoid arthritis?

In severe cases, affected individuals may develop abnormal inflammation, leading to severe joint damage, which limits movement and can cause significant disability.

A few other complications include:

  • Osteoporosis
  • Rheumatoid nodules (tiny firm bumps that develop around the pressure areas)
  • Dry eyes and mouth (a disorder characterized by a decrease in the amount of moisture in the eyes and mouth)
  • Carpal tunnel syndrome (compression of the median nerve leading to numbness and tingling pain in the hand and forearm) 
  • Heart problems
  • Lung disease
  • Lymphoma (cancer in the lymph system)

How is rheumatoid arthritis treated?

Currently, there is no permanent cure for rheumatoid arthritis (RA). Treatment generally involves a combination of medication and therapies to curb inflammation or stop the disease progression.

SLIDESHOW

What Is Rheumatoid Arthritis (RA)? Symptoms, Treatment, Diagnosis See Slideshow

Health Solutions From Our Sponsors

Medically Reviewed on 10/21/2022
References
Image Source: iStock image

Rheumatoid Arthritis Cleveland Clinic: https://my.clevelandclinic.org/health/diseases/4924-rheumatoid-arthritis

What is rheumatoid arthritis? Versus Arthritis: https://www.versusarthritis.org/about-arthritis/conditions/rheumatoid-arthritis/

Rheumatoid arthritis Medline Plus: https://medlineplus.gov/genetics/condition/rheumatoid-arthritis/#resources

Genetics of Rheumatoid Arthritis — A Comprehensive Review NIH: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3655138/