A rare, moderate form of hypophosphatasia (HPP) characterized by onset after six months of age and widely variable clinical features from low bone mineral density for age, to unexplained fractures, skeletal deformities, and rickets with short stature and waddling gait. The disease is Experimental Factor Ontology id EFO_0021432 (childhood-onset hypophosphatasia). Also known as: Childhood-onset Rathbun disease, Childhood-onset phosphoethanolaminuria.