Congenital Erythropoietic Porphyria: Characterization of Murine Models of the Severe Common (C73R/C73R) and Later-Onset Genotypes

Mol Med. 2011;17(7-8):748-56. doi: 10.2119/molmed.2010.00258. Epub 2011 Feb 25.

Abstract

Congenital erythropoietic porphyria (CEP) is an autosomal recessive disorder due to the deficient activity of uroporphyrinogen III synthase (UROS). Knock-in mouse models were generated for the common, hematologically severe human genotype, C73R/C73R, and milder genotypes (C73R/V99L and V99L/V99L). The specific activities of the UROS enzyme in the livers and erythrocytes of these mice averaged approximately 1.2%, 11% and 19% of normal, respectively. C73R/C73R mice that survived fetal life to weaning age (~12%) had a severe microcytic hypochromic anemia (hemoglobin 7.9 g/dL, mean cellular volume 26.6 fL, mean cellular hemoglobin content 27.4 g/dL, red cell distribution width 37.7%, reticulocytes 19%) and massively accumulated isomer I porphyrins (95, 183 and 44 μmol/L in erythrocytes, spleen and liver, respectively), but a nearly normal lifespan. In adult C73R/C73R mice, spleen and liver weights were 8.2- and 1.5-fold increased, respectively. C73R/V99L mice were mildly anemic (hemoglobin was 14.0 g/dL and mean cellular hemoglobin was 13.3), with minimally accumulated porphyrins (0.10, 5.54 and 0.58 μmol/L in erythrocytes, spleen and liver, respectively), whereas adult V99L/V99L mice were normal. Of note, even the mildest genotype, V99L/V99L, exhibited porphyria in utero, which disappeared by 2 months of age. These severe and mild mouse models inform therapeutic interventions and permit further investigation of the porphyrin-induced hematopathology, which leads to photo-induced cutaneous lesions. Of significance for therapeutic intervention, these mouse models suggest that only 11% of wild-type activity might be needed to reverse the pathology in CEP patients.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Animals, Newborn
  • Disease Models, Animal*
  • Erythrocytes / enzymology
  • Erythrocytes / metabolism
  • Erythrocytes / pathology
  • Female
  • Genotype
  • Humans
  • Kidney / enzymology
  • Kidney / metabolism
  • Kidney / pathology
  • Liver / enzymology
  • Liver / metabolism
  • Liver / pathology
  • Male
  • Mice
  • Mice, 129 Strain
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Organ Size
  • Phenotype
  • Porphyria, Erythropoietic / enzymology
  • Porphyria, Erythropoietic / genetics*
  • Porphyrins / metabolism
  • Spleen / enzymology
  • Spleen / metabolism
  • Spleen / pathology
  • Time Factors
  • Uroporphyrinogen III Synthetase / genetics*
  • Uroporphyrinogen III Synthetase / metabolism

Substances

  • Porphyrins
  • Uroporphyrinogen III Synthetase