Porphobilinogen deaminase and the synthesis of porphyrin isomers in the Dubin-Johnson syndrome.

Porphyrin synthesis was studied in a family of 9.3 of whom had the Dubin-Johnson syndrome (DJS). Subjects with DJS had modest increases in urinary porphyrin concentration with a marked increase in the series I isomer of coproporphyrin (tetracarboxylic) as well as in the octa-, hepta-, hexa- and penta-carboxyl porphyrins. Activity of erythrocyte porphobilinogen deaminase (PBG-D) was also increased. Non-expressing carriers in the family had normal levels of urinary porphyrins but modest increases in both series I isomer accumulation and PBG-D activity. These results may provide a rationale for the altered synthesis of porphyrin in DJS.

The organelle pathology and demonstration of mitochondrial superoxide dismutase deficiency in two patients with Dubin--Johnson--Sprinz syndrome.

1. Liver biopsies from two patients with the Dubin-Johnson-Sprinz syndrome were subjected to analytical subcellular fractionation by sucrose-density-gradient centrifugation and enzymic microassays. 2. A selective deficiency of mitochondrial superoxide dismutase has been demonstrated in these patients. 3. The significance of this enzyme deficiency is discussed in relation to the organelle pathology of the syndrome.

Uroporphyrinogen III cosynthetase in liver and blood in the Dubin-Johnson syndrome.

The activities of uroporphyrinogen III cosynthetase in blood lysates from five patients with the Dubin-Johnson syndrome (DJS) and four control subjects and in liver homogenates from four patients and four control subjects were determined. No significant difference was found in enzyme activity between the two groups in either blood lysate or liver homogenate. These results indicate that low urinary coproporphyrin III output in the DJS is not due to deficiency of uroporphyrinogen III cosynthetase in the liver and the erythropoietic system.