Changes in hair morphology of mucopolysaccharidosis I patients treated with recombinant human alpha-L-iduronidase (laronidase, Aldurazyme).

Mucopolysaccharidoses (MPS) are heritable, metabolic diseases caused by accumulation of mucopolysaccharides (glycosaminoglycans, GAGs) in lysosomes. This accumulation is due to a deficiency in one of several specific enzymes involved in the degradation of GAGs. MPS type I (MPS I) is caused by low or undetectable activity of alpha-L-iduronidase, an enzyme involved in removing the terminal iduronic acid residues from heparan and dermatan sulfate. Recently, an enzyme replacement therapy (ERT) for MPS I, based on administration of recombinant human alpha-L-iduronidase (laronidase, Aldurazyme), became available. The assessment of efficacy of ERT is especially important because MPS I is a highly variable and very rare disease, and the clinical trials involved relatively low number of patients. Among various significant clinical improvements during ERT, remarkable changes in hair morphology were noted. Detailed studies of hair samples from one patient, who did not have a hair cut from the beginning of ERT to the end of this study, and supported by results obtained for two other patients, revealed hair shaft structural abnormalities in MPS I hair. These hair abnormalities disappeared upon treatment with Aldurazyme. Although hair morphology is of limited clinical importance, the data suggest that changes in this parameter could be a useful, additional tool for a rapid, non-invasive, preliminary assessment of ERT efficacy.