ABCC6 and Pseudoxanthoma elasticum: A recent clinical study reported that PXE patients have a higher OA score in knee and articular joints (Gielis et al., 2020), however, no effects on long bone mineral density in PXE patients and Abcc6 knockout mice has been noted (Li et al., 2009; Jiang and Uitto, 2012; Martin et al., 2017).