Abstract
BACKGROUND: Camptodactyly-arthropathy-coxa vara-pericarditis (CACP) syndrome, caused by biallelic pathogenic mutations in the proteoglycan 4 (PRG4) gene, is characterized by early-onset camptodactyly, noninflammatory arthropathy, coxa vara deformity, and rarely, pericardial effusion. This syndrome can mimic juvenile idiopathic arthritis. CACP syndrome is caused by mutations in the proteoglycan 4 (PRG4) gene. To date, only 36 pathogenic mutations have been reported in this gene, but none have been reported from Azerbaijan. CASE PRESENTATION: Herein, we report two siblings presented with chronic polyarthritis, had a prior diagnosis of juvenile idiopathic arthritis, but was subsequently diagnosed as CACP syndrome with novel mutation in the PRG4 gene. CONCLUSION: Our report expands the knowledge of PRG4 mutations, which will aid in CACP patient counseling.