The mechanisms that regulate FGF23 secretion in bone cells are only partially known.Lessons from genetic diseases such as XLH and AHRH1 have taught that disturbances in themineralization of the organic matrix surrounding FGF23-producing cells can be a strongstimulus for their FGF23 secretion (Fenget al. 2006). This evidence concerns the gene FGF23 and hereditary disease.