chronic autoimmmune, multisystem disorder. Inflammatory proliferative synovitis that often progresses to joint destruction and ankylosis (fusion)

Demographics: Prevalence ~1%, Females 4:1, 30-60

Aetiology:

idiopathic: Genetic + Env. + Autoimmune

• Genetic Susceptibility: HLA DRB1 in 75%, PTPN22 gene polymorphism.
• Environmental Factor: ? EBV, Borrelia etc.
• Autoimmunity: IGM anti IgG (RF). Anti CCP Ab, T lymphocytes against collagen & cartilage glycoprotein 39, Macrophages around RF → type III (imm. complex)
  • CCP: Cyclic Citrullinated Peptides (collagen, fibrinogen, vimentin etc).

Risk Factors:

• FHx
• HLA-DRB1
• smoking
• hormonal (premenopause)
• obesity
• infection

Pathophysiology