As for why SLCO2A1 mutant female could be free of the typical PHO symptoms (digital clubbing, pachyderma, periostosis and et al.)presented in males, it might involve the differences of sex hormones of males and females as well as the deregulation of PGE2 or even PGF2α. Here, SLCO2A1 is linked to primary hypertrophic osteoarthropathy.