FIBROBLAST SILVER LOADING FOR THE DIAGNOSIS OF MENKES-DISEASE

Menkes disease is a genetic disorder of copper metabolism. Copper upta ke and retention assays on fibroblast or amniotic fluid cell cultures have been used for pre-and postnatal diagnosis. These copper loading t ests are complicated by the use of Cu-64, which is not commonly availa ble and has a very short (12.8 hours) physical half life. Besides copp er, silver is also a substrate for the bacterial homologue of the Menk es transport protein. We report here that loading tests using radioact ive silver (Ag-110m), instead of copper, can be used for the diagnosis of Menkes disease. Ag-110m is commercially available and has a conven ient physical half Life of 250 days, which makes it suitable for use i n diagnostic laboratories. Our studies support the hypothesis that red uction of divalent to monovalent copper is an essential step preceding transport.