However, addition of FK506 to cell cultures delays collagen folding only slightly [34], and absence of FKBP65 in patients with OI, Bruck syndrome and Kuskokwim disease has negligible effects on collagen helical folding [36]–[38], limiting FKBP65 to at most a compensatory role in the absence of CyPB. Here, FKBP10 is linked to osteogenesis imperfecta.