Scientific progress has been rapid in lysosomal biology during the last six decades. Its application to human disease is nothing less than spectacular. In no other group of disorders has knowledge and clinical utility progressed so speedily. Recall that the organelle was described in just 1955. Since then, the biochemical alterations and storage materials were described, the enzyme deficiencies discovered, the gene coding of these glycoproteins cloned and thousands of mutations defined. These advances have resulted in highly improved diagnosis for more than 50 diseases. For five diseases,...