Keywords: AICAR; Amino-imidazole carboxamide ribonucleotide; CD; Crohn's disease; GPA; Granulomatosis with polyangiitis; IBD; Inflammatory bowel disease; JIA; Juvenile idiopathic arthritis; MRP; MTX; Methotrexate; Myeloid-related protein; SNP; Single nucleotide polymorphism.