Porphyrins in Dubin-Johnson Syndrome

To the Editor: I have some questions and comments about the article by Wolkoff et al. entitled “Inheritance of the Dubin-Johnson Syndrome” (N Engl J Med 288:113, 1973). The authors, and others previously, have observed both decreased urinary excretion of coproporphyrin III and increased excretion of coproporphyrin I in the Dubin-Johnson syndrome, yielding an abnormally high ratio of I-isomer excretion. The “obligate heterozygotes” do not conform to this pattern in that decreased III-isomer excretion is not associated with increased I-isomer excretion to yield only a 7 per cent increase in percentage of coproporphyrin I excretion vs. controls. Although the authors.