Informed consent is obtained from the participant or from the parent / legal guardian The participant is clinically suspected for HPP The participant does not have pathogenic variant/s in the ALPL gene The participant showed low alkaline phosphatase levels (age- and sex-adjusted) on at least two occasions at least a month apart based on the local laboratory reference range  None of these conditions are present:  Celiac disease and Clofibrate therapy and Cleidocranial dysplasia and Cushing's syndrome and Hypothyroidism and Massive Blood transfusion and Milk-alkali syndrome and Multiple myeloma and Osteogenesis imperfecta, type II and Pernicious or profound anemia and Starvation and Vitamin C deficiency and Vitamin D intoxication and Zinc deficiency and Magnesium deficiency