Systemic-onset disease

Juvenile idiopathic arthritis (formerly juvenile chronic arthritis in Europe and juvenile rheumatoid arthritis in North America) is an umbrella term used to describe a heterogeneous group of several disease subtypes occurring in someone who is less than 16 years old that lasts for more than six weeks and are of unknown cause (1).

• it is the most common rheumatologic condition of childhood
• consists of subtypes which includes -
  • oligoarticular - affecting 1-4 joints
  • polyarticular - 5 or more joints are affected
  • systemic onset (1,2)

The aetiology of this condition is thought to be multifactorial with both environmental and genetic factors playing key roles

• most common risk factors are infections in combination with genetic susceptibility. In addition stress and maternal smoking have also been reported to be involved in the pathogenesis
• multiple genes have been shown to be associated with the aetiology of JIA .
  • human leukocyte antigen (HLA) B27 and the other HLA tissue types are the most common genes involved (1,3)

Note that the term Still's disese, which has in the past been used generically in this condition, is now taken to imply systemic onset juvenile chronic arthritis.

Reference:

• (1) Prince FH, Otten MH, van Suijlekom-Smit LW. Diagnosis and management of juvenile idiopathic arthritis. BMJ. 2010;341:c6434
• (2) Oberle EJ, Harris JG, Verbsky JW. Polyarticular juvenile idiopathic arthritis – epidemiology and management approaches. Clinical Epidemiology. 2014;6:379-393.
• (3) Barut K, Adrovic A, Şahin S, Kasapçopur Ö. Juvenile Idiopathic Arthritis. Balkan Medical Journal. 2017;34(2):90-101.