BTG3 and juvenile idiopathic arthritis: N: number; JIA: juvenile idiopathic arthritis; yr: years; BMI: body mass index; BMI SDS: BMI standard deviation score; ANA: antinuclear antibody; RF: rheumatoid factor; HLA- B27: Human Leukocyte antigen-B27; JADAS-27: juvenile arthritis disease activity score-27; MTX: methotrexate; NSAIDs: non steroid anti-inflammatory drugs