While enamel and dentin defects in mouse models of HPP are well-represented in reports on developmental phenotypes, the longer lifespan of cKO vs. Alpl−/− mice allowed assessment of tissues later in life, leading to the first observation of severe periodontal bone loss in a mouse HPP model (yellow dotted lines showing alveolar crest height in Figures 1F vs. 1H). This evidence concerns the gene ALPL and hypophosphatasia.