In patients with HPP, with or without treatment, several types of ectopic calcifications are commonly observed: ocular calcification, nephrocalcinosis, and painful periarthritis.(22, 23, 65, 66, 67, 68, 69, 70, 71) Our AAV8‐TNAP‐D10‐treated Alpl−/− mice did not develop nephrocalcinosis, kidney stones, or structural changes in the glomeruli or renal tubules as observed under light microscopy. This evidence concerns the gene ALPL and periarthritis.