ALPL and osteomalacia: Specifically, the genetic disorder hypophosphatasia (HPP), a rare form of inherited rickets, osteomalacia and hypomineralisation of teeth, is caused by loss of function mutations in the alkaline phosphatase (ALPL) gene which encodes for the ectoenzyme tissue-nonspecific alkaline phosphatase (TNAP) (Millán and Whyte, 2016; Robison, 1923).