Immunochemical study of uroporphyrinogen decarboxylase in a patient with mild hepatoerythropoietic porphyria.

Abstract

Hepatoerythropoietic porphyria (HEP) is due to a marked deficiency of uroporphyrinogen (URO) decarboxylase, a cytosolic enzyme in the heme biosynthetic pathway. Using a radioimmunoassay method, we determined the concentration of URO decarboxylase protein in erythrocytes from a patient with mild HEP and found that the enzyme protein concentration had markedly decreased to less than 7% of the normal controls. This finding, however, was in contrast to the enzyme activity in the patient's erythrocytes, which was 16% of normal control levels and different from previously reported HEP cases in that erythrocytes in our patient contained disproportionately elevated URO decarboxylase activity in comparison to its immunoreactive material. Our findings suggests the possibility of a mutant isozyme in this patient that is not immunoreactive with an antibody raised against the normal enzyme.

• Authors: H Fujita, S Sassa, A C Toback, A Kappas
• Journal: The Journal of clinical investigation (J Clin Invest) Vol. 79 Issue 5 Pg. 1533-7 (May 1987) ISSN: 0021-9738 [Print] United States
• PMID: 3571497 (Publication Type: Case Reports, Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Isoenzymes
• Carboxy-Lyases
• Uroporphyrinogen Decarboxylase

Topics

• Adult
• Carboxy-Lyases (deficiency)
• Erythrocytes (enzymology)
• Female
• Histocytochemistry
• Humans
• Isoenzymes (blood)
• Liver Diseases (enzymology, genetics)
• Male
• Middle Aged
• Porphyrias (enzymology, genetics)
• Radioimmunoassay
• Uroporphyrinogen Decarboxylase (blood, deficiency)