Of mice and men, metals and mutations

Several mutations affecting the transport of copper and zinc in humans and in mice have been discovered over the last 15 years, joining the long known disturbance of copper transport in Wilson's disease. Menkes' disease (classical and mild variant forms) and X linked Ehlers-Danlos syndrome (type IX, X linked cutis laxa) have features in common with one another and with the brindled (Mobr) and blotchy (Moblo) mouse mutants, respectively. There may be one allelic series of mutants in each species or two loci may be involved in each. The toxic milk mutant (tx) in the mouse may be homologous to Wilson's disease in man. The defect of intestinal absorption of zinc in acrodermatitis enteropathica has no homologue yet in the mouse. However, the lethal milk (lm) mutant in the mouse may be homologous to a condition of zinc deficiency described in a few breastfed, low birth weight infants. Many more genetic defects of transport of copper and of zinc may await discovery. Conversely, these mutants are valuable in elucidating the normal processes of copper and zinc transport.