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This study aims to ascertain the genetic variants which contribute to the most common types of MPS in eleven Iranian families. Clinical and biochemical features were obtained during initial examination and patients were further investigated for genetic defects in the MPS genes. Peripheral blood samples were obtained from all family members after obtaining written informed consent. Based on the patient's clinical diagnosis, three different genetic tests including Sanger sequencing of four genes (IDUA, IDS, SGSH, and GALNS), targeted panel (10 genes) and Whole Exome Sequencing (WES) techniques were applied to identify the causative variants. A total of 12 different mutations were identified in five genes, including nine novel mutations and three previously reported missense mutations. Sanger sequencing confirmation of the identified mutations determined one case of compound heterozygous in the NAGLU gene. In this study, novel mutations in MPS related genes were identified attempting to characterize the type and subtype of the disease using molecular approaches. Results of the study positively contribute to mutation spectrum of IDUA, IDS, SGSH, NAGLU, and GALNS genes in the Iranian cohort. It may also enrich genetic counseling for rapid risk assessment and disease management., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: The mucopolysaccharidoses (MPSs) are rare genetic disorders caused by mutations in lysosomal enzymes involved in the degradation of glycosaminoglycans (GAGs). In this study, we analyzed a total of 48 patients including MPSI (n=6), MPSII (n=18), MPSIIIA (n=11), MPSIVA (n=3), and MPSVI (n=10)., Methods: In MPS patients, urinary GAGs were colorimetrically assayed. Enzyme activity was quantified by colorimetric and fluorimetric assays. To find mutations, all IDUA, IDS, SGSH, GALNS, and ARSB exons and intronic flanks were sequenced. New mutations were functionally assessed by reconstructing mutant alleles with site-directed mutagenesis followed with expression of wild-type and mutant genetic variants in CHO cells, measuring enzymatic activity, and Western blot analysis of protein expression of normal and mutated enzymes in cell lysates., Results: A total of five novel mutations were found including p.Asn348Lys (IDUA) in MPSI, p.Tyr240Cys (GALNS) in MPSIVA, and three ARSB mutations (p.Gln110*, p.Asn262Lysfs*14, and pArg315*) in MPSVI patients. In case of mutations p.Asn348Lys, p.Asn262Lysfs*14, and p.Gln110*, no mutant protein was detected while activity of the mutant protein was <1% of that of the normal enzyme. For p.Tyr240Cys, a trace of mutant protein was observed with a remnant activity of 3.6% of the wild-type GALNS activity. For pArg315*, a truncated 30-kDa protein that had 7.9% of activity of the normal ARSB was detected., Conclusions: These data further enrich our knowledge of the genetic background of MPSs., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Sanfilippo syndrome (mucopolysaccharidosis type III, MPS III) is a progressive disorder in which patients are characterized by severe central nervous system degeneration together with mild somatic disease. MPS III results from a deficiency in one of the four enzymes involved in the heparan sulfate degradation, with sulfamidase (SGSH), α-N-acetylglucosaminidase (NAGLU), acetyl-coenzyme A: α-glucosaminide N-acetyltransferase (HGSNAT), and N-acetylglucosamine-6-sulfatase (GNS) being deficient respectively in MPS IIIA, MPS IIIB, MPS IIIC and MPS IIID. Mutation screening using PCR reaction/sequencing analysis on genomic DNA fragments was performed in seven Tunisian index cases with MPS IIIA, three with MPS IIIB and two with MPS IIIC. QMPSF (Quantitative Multiplex PCR of Short fluorescent Fragments) analysis was developed for the detection of genomic deletions and duplications in the SGSH gene. These approaches allowed the identification of 11 mutations, 8 of them were novel including a mutation involving the start codon (p.Met1?), one small duplication (p.Leu11AlafsX22), one small deletion (p.Val361SerfsX52) and a large deletion of exon 1 to exon 5 in the SGSH gene, one missense mutation (p.Pro604Leu) and one nonsense mutation (p.Tyr558X) in the NAGLU gene and, finally, one missense mutation (p.Trp627Cys) and one nonsense mutation (p.Trp403X) in the HGSNAT gene., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Heparan sulfates were isolated from the urine of normal individuals and patients with genetic mucopolysaccharidoses after exhaustive digestion with chondroitinase ABC. Electrophoresis of these preparations on cellulose acetate membrane revealed one spot corresponding in mobility to reference heparan sulphate in barium acetate buffer, while electrophoresis in 0.1 M HCl resulted in two distinct spots for each case; one corresponded in migration rate to reference heparan sulfate, and the other was faster in mobility than reference heparan sulfate but slightly retarded when compared with reference heparin. On thin-layer gel filtration on Sephadex G-200 (superfine) heparan sulfate from normal urine was polydispersed in character and its molecular size was larger than those of other preparations. Heparan sulfates from Hunter's and Sanfilippo's urine were monodispersed and small in molecular size. The molecular size of heparan sulfate from Sanfilippo's urine was the smallest of all. Heparin sulfate from Hurler's urine appeared to be composed of two populations; one corresponded in molecular size to heparan sulfate from normal urine, and the other corresponded to that of Hunter's urine.

We studied the residual alpha-N-acetylglucosaminidase activity in two siblings with severe and mild Sanfilippo B syndrome. No striking differences were demonstrated between the mutant enzymes from the severe and the mild case. However we found an altered enzyme activity characterized by displacement of the pH optimum towards basic values compared to the pH optimum of the normal enzyme, higher stability to heat and to Hg2+ ion treatment. It is suggested that the Sanfilippo B disease in this sibship is due to a mutation of a structural gene coding for alpha-N-acetylglucosaminidase.