Hypophosphatasia

Excerpt

Hypophosphatasia is a rare inborn error of metabolism that occurs in approximately one per 100,000 live births [1]. Hypophosphatasia is characterized by defective mineralization of bone and/or teeth in the context of low activity of serum and bone alkaline phosphatase(ALP). Reduced serum ALP activity, increasing phosphoethanolamine, inorganic pyrophosphates and pydoxal-5’-phosphate in serum and urine determine the diagnosis of hypophosphatasia [2]. Hypophosphatasia is due to mutations in the alkaline phosphatase gene encoding the tissue nonspecific alkaline phosphatase. The deficiency of ALP limits the availability of phosphate giving rise to serum phosphate decreasing and serum calcium increasing without phosphate to interact with, and the failure to form the Ca-PO4 matrix leads to fragile bones and early loss of teeth. Clinical presentation widely varies, from death in utero to cases in which pathologic fractures first present only in adulthood [3]. Adults may be troubled by recurring fractures in their feet and painful, partial fractures in their long bones. Some patients can be self-limited or self-cure. At present, there is no curative treatment for hypophosphatasia. …