Arthritis in Two Patients With Partial Recombination Activating Gene Deficiency

Area of Science:

• Immunology
• Genetics
• Rheumatology

Background:

• Primary immunodeficiencies (PIDs) are increasingly associated with autoimmune complications.
• Recombination Activating Gene (RAG) defects are a type of combined immunodeficiency that can manifest with immune dysregulation.
• Treating autoimmunity in PIDs requires balancing immunosuppression with infection risk.

Observation:

• Inflammatory arthritis is a recognized clinical feature in some PIDs.
• Standard treatments like disease-modifying anti-rheumatic drugs (DMARDs) may not be optimal for all PID-associated arthritis.
• Tocilizumab, an IL-6 signaling inhibitor, has shown efficacy in other immune dysregulation syndromes like STAT3 gain-of-function mutations.

Findings:

• Two cases of PID with RAG defects and refractory inflammatory arthritis were identified.
• One patient experienced significant symptom improvement with tocilizumab therapy.
• This suggests arthritis can be a manifestation of immune dysregulation in RAG deficiency.

Implications:

• Tocilizumab therapy may be a valuable treatment option for arthritis in patients with RAG deficiency.
• Mechanism-based therapies targeting specific inflammatory pathways offer new avenues for managing complex PID phenotypes.
• Further research is warranted to explore the role of IL-6 blockade in RAG-associated arthritis.