Staining with Alcian blue in various concentrations of magnesium chloride (alcianophilia) has been found to be a useful supplement to metachromatic staining to detect increased cellular concentrations of glycosaminoglycans (mucopolysaccharides). In many instances alcianophilia at 0.3 M MgCl2 is more specific than metachromasia and does not give "false positives" sometimes found in normal individuals and in those with cystic fibrosis, Gaucher’s disease, familial amaurotic idiocy, and pseudoxanthoma elasticum. On the other hand, it gives a "false negative" reaction in the Sanfilippo syndrome (perhaps because the characteristically elevated glycosaminoglycan in this disease, heparan sulfate, is not synthesized by cultured skin fibroblasts), and in the Marfan syndrome. It detects the Maroteaux-Lamy syndrome, which metachromasia does not.
The "false positives" given by metachromasia in all six families studied thus far are genuine, reproducible reactions that can be traced through at least three generations of normal individuals within a family. There is therefore, in these families, a genetic factor that causes such metachromasia, but it is not increased glycosaminoglycan concentration.