Mucopolysaccharidosis I (MPS-I) is an autosomal recessive lysosomal storage diseases, caused by α-L-iduronidase (IDUA) enzyme deficiency. The clinical manifestations of MPS-I patients are variable ranging from severe to mild, and therefore prediction of disease severity is difficult. From when IDUA gene has been cloned more than 109 distinct mutations have been identified in it and this number is increasing. This mutation analysis has provided some molecular explanations for the range of MPS-I

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... henotypes. The aim of this study was identification and molecular characterization of IDUA gene mutations in our subset of MPS I patients. Methods: The present study performed on 5 Iranian families, each with a suspected child for MPS-I. Initially by using enzyme activity assay, the Hurler syndrome was verified and then presence of L123R mutation was evaluated by PCR-SSCP. Finally by PCR amplification of all 14 exons of the gene, SSCP and sequencing the mutations underlying the disease were identified and characterized. Results: The detected mutations turned to be L123R (in 2 patients), W402X, P533R and G51D mutations in other 3 patients. Discussion: L123R mutation, which was reported for the first time from our centre, was also present in 2 of the patients of this study but other 3 mutations were not novel. From our results, as well others, it can be concluded that the range of mutations in IDUA gene differ in different geographical areas. This should be considered when designing mutation detection strategies for MPS-I.