Acrodermatitis enteropathica and the relation to pellagra

A patient with a variant form of acrodermatitis enteropathica (AE) without hypozincemia is presented who showed a rise in plasma zinc and partial improvement on a pancreatic enzyme preparation, apparently because of its content of picolinic acid (PA). Complete recovery occurred on 60 mg zinc (1). This patient has now been treated with zinc PA (equal to only 5 mg zinc) and subsequently with PA. Both maintained elevated plasma zinc levels. Because of the similarity of AE with pellagra and the common origin of PA and nicotinic acid from tryptophan, a hypothesis is presented which suggests that skin manifestations in the two disorders are due to PA deficiency since picolinic carboxylase forms NAD preferentially when there is competition for the common precursor.