What is hypophosphatasia?
Hypophosphatasia results from inherited inactivating mutations of the gene that encodes the tissue nonspecific alkaline phosphatase isoenzyme (ALPL).
The severity of the enzyme defect determines the clinical features, which vary from fetal demise to disabling pediatric forms to milder adult forms manifested by rickets or osteomalacia, dental abnormalities, multiple fractures, or just osteoporosis.
Low serum alkaline phosphatase, elevated vitamin B6 or pyridoxal phosphate, and high urine phosphoethanolamine levels suggest the diagnosis, which can be confirmed with genetic testing.
Recently, enzyme replacement, asfotase alpha, has become available for treatment.
3 Interesting Facts of Hypophosphatasia
- Autosomal dominant and autosomal recessive inheritance of defective bone mineralization, resulting in mild to severe forms of disease secondary to low bone mineral density
- Hallmark is low alkaline phosphatase level
- Other supporting laboratory test results include elevated levels of inorganic pyrophosphate, pyridoxal 5-phosphate, and phosphoethanolamine
- Early loss of teeth is characteristic