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Research Article Free access | 10.1172/JCI107068
Department of Internal Medicine, University of Texas Southwestern Medical School at Dallas, Dallas, Texas 75235
Department of Medicine, University of Southern California School of Medicine, Los Angeles, California 90007
Find articles by Strand, L. in: JCI | PubMed | Google Scholar
Department of Internal Medicine, University of Texas Southwestern Medical School at Dallas, Dallas, Texas 75235
Department of Medicine, University of Southern California School of Medicine, Los Angeles, California 90007
Find articles by Meyer, U. in: JCI | PubMed | Google Scholar
Department of Internal Medicine, University of Texas Southwestern Medical School at Dallas, Dallas, Texas 75235
Department of Medicine, University of Southern California School of Medicine, Los Angeles, California 90007
Find articles by Felsher, B. in: JCI | PubMed | Google Scholar
Department of Internal Medicine, University of Texas Southwestern Medical School at Dallas, Dallas, Texas 75235
Department of Medicine, University of Southern California School of Medicine, Los Angeles, California 90007
Find articles by Redeker, A. in: JCI | PubMed | Google Scholar
Department of Internal Medicine, University of Texas Southwestern Medical School at Dallas, Dallas, Texas 75235
Department of Medicine, University of Southern California School of Medicine, Los Angeles, California 90007
Find articles by Marver, H. in: JCI | PubMed | Google Scholar
Published October 1, 1972 - More info
Intermittent acute porphyria has recently been distinguished biochemically from other genetic hepatic porphyrias by the observation of diminished hepatic uroporphyrinogen I synthetase activity and increased δ-aminolevulinic acid synthetase activity. Since deficient uroporphyrinogen I synthetase may be reflected in nonhepatic tissues, we have assayed this enzyme in red cell hemolysates from nonporphyric subjects and from patients with genetic hepatic porphyria. Only patients with intermittent acute porphyria had decreased erythrocyte uroporphyrinogen I synthetase activity which was approximately 50% of normal. The apparent Km of partially purified uroporphyrinogen I synthetase was 6 × 10−6m in both nonporphyrics and patients with intermittent acute porphyria. These data provide further evidence for a primary mutation affecting uroporphyrinogen I synthetase in intermittent acute porphyria. Further-more, results of assay of red cell uroporphyrinogen I synthetase activity in a large family with intermittent acute porphyria suggest that this test may be a reliable indicator of the heterozygous state.