B

PHEX encodes the phosphate-regulating neutral endopeptidase whose loss-of-function leads to X-linked hypophosphatemia, characterized by defective dentin mineralization; experimental inhibition or mutation of PHEX disrupts odontoblast activity and produces hypomineralized dentin, whereas the other listed genes are not directly linked to dentin matrix mineralization [Lv 2011, PMID 21324501; Boukpessi 2010, PMID 20581062].