The importance of PRG4 to joint hemostasis is evidenced in the loss-of-function mutations in the Prg4 gene in the autosomal recessive disease, camptodactylyl-arthropathy-coxa vara pericarditis (CACP) syndrome, characterized by juvenile-onset arthropathy [4, 5]. Here, PRG4 is linked to camptodactyly-arthropathy-coxa vara-pericarditis syndrome.