Lysosomal transport disorders

In the group of lysosomal storage diseases, transport disorders occupy a sp ecial place because they represent rare examples of inborn errors of metabo lism caused by a defect of an intracellular membrane transporter. In partic ular, two disorders are caused by a proven defect in carrier-mediated trans port of metabolites: cystinosis and the group of sialic acid storage disord ers (SASD). The recent identification of the gene mutations for both disord ers will improve patient diagnosis and shed light on new physiological mech anisms of intracellular trafficking.