A novel mutation in the proteoglycan 4 gene causing CACP syndrome: two sisters report

Pediatr Rheumatol Online J. 2023 Jan 24;21(1):8. doi: 10.1186/s12969-023-00793-z.


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.

Keywords: Arthropathy; Camptodactyly; Coxa vara; PRG4 mutation.

Publication types

  • Case Reports

MeSH terms

  • Arthritis, Juvenile* / genetics
  • Contracture* / genetics
  • Coxa Vara* / diagnostic imaging
  • Coxa Vara* / genetics
  • Female
  • Humans
  • Joint Diseases* / genetics
  • Mutation / genetics
  • Proteoglycans* / genetics
  • Siblings


  • Proteoglycans
  • PRG4 protein, human

Supplementary concepts

  • Jacobs syndrome