Zinc dependency as a cause of chronic diarrhea in variant acrodermatitis enteropathica

Two siblings with chronic diarrhea, growth failure, mood changes, and occasional cheilosis responded repeatedly to treatment with either pharmacologic doses of zinc or pancreatin (Viokase), and their symptoms were exacerbated after withdrawal of therapy. Pancreatic exocrine deficiency was ruled out in both cases. Proteolytic activity was 20% of normal in one infant tested. Plasma zinc concentration was normal. Plasma picolinic acid concentration was low in these two patients and in one previously reported patient (mean 3.6, normal 12.4 +/- 3.3 mumoles/liter). This is a characteristic shared with acrodermatitis enteropathica. The response to Viokase may be due to its content of picolinic acid and/or zinc or the correction of a deficiency of carboxypeptidase, a zinc-requiring enzyme.