Introduction
Psoriatic arthritis (PsA) is a form of arthritis that impacts individuals dealing with psoriasis, an autoimmune skin condition characterized by itchy and scaly skin. This arthritis variant leads to swollen, stiff, or painful joints, often worsening over time. The exact reason some psoriasis sufferers develop psoriatic arthritis is not entirely understood by researchers. There appears to be a significant genetic factor, as many individuals who develop PsA have close family members also affected by the condition. In psoriatic arthritis, immune cells mistakenly attack healthy joint cells, causing inflammation. Researchers have identified certain genes that might contribute to the onset of this immune response, suggesting a complex interplay of multiple genes in the development of PsA.
What Is Psoriasis?
Psoriasis is a chronic skin disease characterized by the development of itchy, scaly patches, often found on areas like the knees, elbows, trunk, and scalp. This common and persistent condition has no cure, and it can bring about discomfort, disrupt sleep, and pose challenges to concentration. The course of psoriasis typically involves cycles marked by flare-ups lasting for several weeks or months, followed by periods of subsiding symptoms. Individuals with a genetic predisposition to psoriasis may find common triggers include infections, injuries such as cuts or burns, and certain medications.
What Is Psoriatic Arthritis?
Psoriatic arthritis, associated with the chronic skin and nail condition psoriasis, exhibits characteristics similar to rheumatoid arthritis (RA) in symptoms and joint inflammation. However, it typically affects fewer joints than RA and does not produce the usual RA antibodies. Psoriatic arthritis manifests in five distinct forms:
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Arthritis affects the small joints in the fingers, toes, or both.
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Asymmetrical arthritis involves the joints in the hands and feet.
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Symmetrical polyarthritis shares similarities with RA.
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Arthritis mutilans is a rare type that causes joint destruction and deformation.
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Psoriatic spondylitis involves arthritis in the lower back (sacroiliac sac) and the spine.
What Is the Association Between Psoriatic Arthritis and Genetics?
Around 20 to 30 percent of individuals with psoriasis develop psoriatic arthritis, typically experiencing arthritis symptoms about ten years after the onset of skin symptoms. Interestingly, around 15 percent of people see both skin and arthritis symptoms appearing simultaneously. Scientists are still unraveling why psoriatic arthritis affects some individuals with psoriasis while others remain unaffected. A combination of genetic and environmental factors plays a role in this phenomenon.
In the realm of genetics, approximately 33 to 50 percent of those with psoriatic arthritis have a sibling or parent with the same condition. Some genes linked to psoriatic arthritis are located in the human leukocyte antigens (HLA) region on chromosome six, associated with immune function.
Additionally, non-HLA genes related to immune function are also considered potential contributors. A comprehensive 2021 review of studies explored existing evidence to identify consistent genetic markers for psoriatic arthritis. While no strong evidence supported individual genetic markers, moderate evidence pointed to six genetic markers associated with psoriatic arthritis in people with psoriasis. These markers include two variations of the HLA-B27 gene, one variation each of the HLA-B38 and HLA-B39 genes, the presence of HLA-B*12, and the presence of polymorphism rs1800925 in the IL13 gene.
What Proportion of Individuals With PsA Have Family Members Affected by the Condition?
Approximately 33 to 50 percent of people diagnosed with psoriatic arthritis have first-degree relatives who also have psoriasis. A first-degree relative, in this context, refers to a family member who shares half of the DNA, such as a biological parent or a full sibling. The heritability of psoriatic arthritis is estimated to be around 80 percent. Trusted source indicates that genetic factors influence a significant portion of the condition's likelihood.
What Are the Associated Risk Factors of Psoriatic Arthritis?
As noticed by the National Institute of Arthritis and Musculoskeletal and Skin Diseases, psoriatic arthritis commonly follows a diagnosis of psoriasis, with symptoms manifesting approximately 7 to 10 years after the onset of skin symptoms. While psoriatic arthritis can develop at any age, its prevalence increases, peaking slightly before reaching 60 years. In a 2021 review, researchers identified a moderate correlation between psoriatic arthritis and certain symptoms, such as sores in the buttock fold and nail pitting. However, evidence regarding associations with obesity or the severity of psoriasis was conflicting.
Another 2021 study delved into potential risk factors for various arthritis conditions, revealing distinct associations. Psoriatic arthritis, for instance, showed links with obesity, pharyngitis, and skin infections. Psoriasis shared associations with obesity and moderate alcohol intake, while rheumatoid arthritis correlated with gout. On the other hand, ankylosing spondylosis exhibited a connection with uveitis, characterized by swelling in the middle layer of the eye.
Can Genetic Testing Predict the Chances of Developing Psoriatic Arthritis?
In a study conducted in 2020, researchers discovered that genetic testing has a limited ability to predict the future onset of psoriatic arthritis in individuals with psoriasis. The development of psoriatic arthritis is influenced by a combination of genes, with some, like HLA-B27, showing a moderate association with PsA. However, even if an individual possesses this gene, it does not guarantee the development of psoriatic arthritis. As researchers deepen their understanding of the genetic factors contributing to psoriatic arthritis, genetic testing may become more precise in predicting the likelihood of its occurrence.
How Is Psoriatic Arthritis Diagnosed?
Confirmation of psoriatic arthritis is facilitated if someone is already diagnosed with psoriasis. With evident skin symptoms, diagnosis becomes easier. The diagnostic process initiates with a thorough health history and physical examination. The healthcare provider will inquire about the symptoms, and blood tests may be conducted, including:
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Erythrocyte Sedimentation Rate (ESR or Sed Rate): This test assesses the rate at which red blood cells settle at the bottom of a test tube. In swelling and inflammation, blood proteins clump together, causing them to fall more rapidly. The speed of this descent correlates with the severity of inflammation.
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Uric Acid: While high blood uric acid levels can be observed in psoriatic arthritis, they are not utilized for diagnosis or monitoring.
In addition to blood tests, various imaging techniques such as X-rays, CT scans, ultrasound, MRI, and skin biopsies may aid the diagnostic process.
How Is Psoriatic Arthritis Effectively Managed?
The healthcare provider will recommend treatments tailored to address specific factors:
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Affected Joints: The treatment choice depends on which joints are impacted by arthritis.
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Symptom Severity: The severity of the symptoms is a crucial factor influencing the recommended treatments.
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Impact on Daily Activities: The extent to which symptoms affect daily activities will also guide treatment decisions.
Common treatments for psoriatic arthritis include:
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Over-The-Counter Medications: Such as NSAIDs or Acetaminophen.
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Therapeutic Measures: Cold or heat therapy.
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Corticosteroids: Medications that reduce inflammation.
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Disease-Modifying Antirheumatic Drugs (DMARDs): Medications that modify the course of the disease.
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Therapy: Physical or occupational therapy to enhance mobility and function.
While surgery is a rare necessity for psoriatic arthritis, in cases of joint damage or bone loss, procedures like arthroplasty (joint replacement) might be considered. The healthcare provider or surgeon will guide the patient on the type of surgery required and provide information on what to expect.
Conclusion
In summary, psoriatic arthritis (PsA) is a genetically influenced condition associated with psoriasis, impacting skin and joints. Genetic predisposition is evident in 33 to 50 percent of cases, with an estimated 80 percent heritability. The disease progresses through cycles of flare-ups and remissions, making diagnosis challenging without visible skin symptoms. Effective management involves personalized treatments, considering affected joints and symptom severity, while surgery remains rare. A comprehensive, genetic-informed approach is key to addressing psoriatic arthritis.
