hypophosphatasia

hypophosphatasia, rare hereditary disorder characterized by very low levels of tissue and serum alkaline phosphatase (the enzyme necessary in cell processes such as muscle metabolism and bone formation). The disease is more common in females. Growth of the infant is retarded; permanent stunting may occur, and rickets-like deformities develop. Fractures occur easily, and the deciduous teeth are lost early. The skull is soft, but intracranial pressure is increased, and the cranial sutures close early, resulting occasionally in brain damage or impairment of vision. There is no treatment, and prognosis depends on the age of onset. Severe hypophosphatasia may be fatal in infancy. Milder childhood cases improve spontaneously as the child matures, and, in adulthood, symptoms, apart from a tendency to fracture, may be lacking.