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Benign familial hyperphosphatasemia.
P A Siraganian1, J J Mulvihill, R A Mulivor
1Clinical Epidemiology Branch, National Cancer Institute, Bethesda, MD 20892.
JAMA
|March 3, 1989
Summary
Benign familial hyperphosphatasemia involves elevated alkaline phosphatase levels due to increased intestinal and liver/bone/kidney isoenzymes. Early recognition of this genetic condition avoids unnecessary diagnostic tests for bone or liver disease.
Area of Science:
- Biochemistry
- Genetics
- Clinical Chemistry
Background:
- Elevated serum alkaline phosphatase (ALP) can indicate serious conditions like liver disease, bone disorders, or neoplasms.
- However, benign conditions, including pregnancy, can also cause elevated ALP, necessitating careful differential diagnosis.
Purpose of the Study:
- To investigate the genetic basis and enzyme defect in a family exhibiting benign hyperphosphatasemia.
- To characterize the specific alkaline phosphatase isoenzymes contributing to the observed biochemical abnormality.
Main Methods:
- Serum total alkaline phosphatase activity was measured in all family members.
- Monoclonal antibodies were used to differentiate between intestinal, placental, and tissue-nonspecific (liver/bone/kidney) ALP isoenzymes.
- Guanidine hydrochloride denaturation was employed to further analyze the liver/bone/kidney ALP component.
Main Results:
- All six family members displayed elevated serum total alkaline phosphatase activity.
- Markedly increased intestinal alkaline phosphatase levels (29%-44% of total) were found in all family members.
- Significantly elevated liver/bone/kidney ALP activity was observed in two offspring, with contributions from both liver and bone.
Conclusions:
- The family presented with benign hyperphosphatasemia, characterized by increased intestinal and tissue-nonspecific ALP isoenzymes.
- The inheritance pattern suggests complex regulation of at least two different alkaline phosphatase genes.
- Early identification of this benign biochemical abnormality is crucial to prevent unnecessary diagnostic investigations.