CACP: Study on Camptodactyly - Arthropathy - Coxa Vara - Pericarditis (CACP) Syndrome

CACP syndrome is a rare autosomal recessive disorder characterized by the triad of camptodactyly, non-inflammatory arthropathy with synovial hyperplasia, and coxa vara. Occasionally, non-inflammatory pericarditis and pleural effusion may also occur. This syndrome is likely underdiagnosed due to its rarity. Epidemiological information is limited to isolated case reports or small patient series, with the largest reported cohort including 35 patients. The genetic cause of CACP syndrome is associated with mutations in the PRG4 gene, located on chromosome 1q31.1. While clinical signs (camptodactyly, non-inflammatory arthropathy, and coxa vara) and radiological findings suggest the diagnosis, genetic testing confirms it by identifying pathogenic biallelic mutations in PRG4. To date, twenty-two mutations have been identified, all leading to premature stop codons and the absence of functional