Treatment of lysosomal storage disorders

Increased awareness and diagnosis are important as treatment is now feasible

The lysosomal storage disorders have hitherto justifiably been consigned to the small print sections of textbooks of biochemistry and internal medicine and optional modules of the undergraduate medical curriculum. However, new treatments may halt–or even reverse–progressive organ damage. The substantial morbidity and premature mortality of these disorders may be preventable.

The lysosomal storage disorders are a group of 40 or so rare disorders, due to inherited deficiency of individual enzymes. Organ damage arises from progressive accumulation of the substrates for the missing enzyme. The commonest lysosomal storage disorders, with an incidence of 1 in 60 000-120 000,1^–3 are Gaucher's disease (glucocerebrosidase deficiency), Anderson-Fabry disease (α galactosidase deficiency), and mucopolysaccharidosis I (α l-iduronidase deficiency). Enzyme replacement therapy for each of these three conditions is licensed and available in Europe.

The rarity of these disorders makes the potential market for therapeutic products very small while the costs of research, development, clinical trials, and marketing are comparable to those for drugs with a much larger potential market. Furthermore, it is not enough simply to treat patients with recombinant enzymes– modifications must be made so that the infused enzyme is targeted to lysosomes in relevant cells and tissues.

Glucocerebrosidase (Cerezyme, Genzyme Corporation, Massachusetts, United States) has been available for over 10 years and …