1. Mucopolysaccharidosis type VI phenotypes-genotypes and antibody response to galsulfase.
- Author
-
Brands, Marion M., Hoogeveen-Westerveld, Marianne, Kroos, Marian A., Nobel, Willemieke, Ruijter, George J., Özkan, Lale, Plug, Iris, Grinberg, Daniel, Vilageliu, Lluïsa, Halley, Dicky J., van der Ploeg, Ans T., and Reuser, Arnold J.
- Subjects
MUCOPOLYSACCHARIDOSIS ,MAROTEAUX-Lamy syndrome ,LYSOSOMAL storage diseases ,THERAPEUTIC use of enzymes ,PHENOTYPES ,GENOTYPE-environment interaction - Abstract
Background: Mucopolysaccharidosis type VI (Maroteaux-Lamy syndrome; MPS VI) is an autosomal recessive lysosomal storage disorder in which deficiency of N-acetylgalactosamine 4-sulfatase (arylsulfatase B; ARSB) leads to the storage of glycosaminoglycans (GAGs) in connective tissue. The genotype-phenotype correlation has been addressed in several publications but the picture is not complete. Since 2007, enzyme-replacement therapy (ERT) has been available for patients with MPS VI in the Netherlands. The purpose of our study was to learn more about the genotype-phenotype correlations in MPS VI and the antibody response to ERT with galsulfase (recombinant human arylsulfatase B). Methods: We identified ARSB mutations in 12 patients and used site-directed mutagenesis to study their effect. Antibody levels to galsulfase were measured using ELISA and a semi-quantitative immunoprecipitation method. We assessed the inhibitory effect of antibodies on galsulfase uptake and their effect on clinical outcome. in vitro Results: Five patients had a rapidly progressive phenotype and seven a slowly progressive phenotype. In total 9 pathogenic mutations were identified including 4 novel mutations (N301K, V332G, A237D, and c.1142 + 2 T > C) together composing 8 pathogenic genotypes. Most mutations appeared not to affect the synthesis of ARSB (66 kD precursor), but to hamper its maturation (43 kD ARSB). Disease severity was correlated with urinary GAG excretion. All patients developed antibodies to galsulfase within 26 weeks of treatment. It was demonstrated that these antibodies can inhibit the uptake of galsulfase . in vitro Conclusions: The clinical phenotypes and the observed defects in the biosynthesis of ARSB show that some of the mutations that we identified are clearly more severe than others. Patients receiving galsulfase as enzyme-replacement therapy can develop antibodies towards the therapeutic protein. Though most titers are modest, they can exceed a level at which they potentially affect the clinical outcome of enzyme-replacement therapy. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF