Phosphomannomutase deficiency is the main cause of carbohydrate-deficient glycoprotein syndrome with type I isoelectrofocusing pattern of serum sialotransferrins. - Jaeken,J.; Artigas,J.; Barone,R.; Fiumara,A.; de Koning,T.J.; Poll-The,B.T. (J Inher Metab Dis, 1997)