PURPOSE: Mucopolysaccharidosis type II (MPS II or Hunter syndrome) is a rare lysosomal storage disorder caused by iduronate-2-sulfatase (IDS) deficiency. MPS II causes a wide phenotypic spectrum of symptoms ranging from mild to severe. IDS activity, which is measured in leukocyte pellets or fibroblasts, was reported to be related to clinical phenotype by Sukegawa-Hayasaka et al. Measurement of residual plasma IDS activity using a fluorometric assay is simpler than conventional measurements using skin fibroblasts or peripheral blood mononuclear cells. This is the first study to describe the relationship between plasma IDS activity and clinical phenotype of MPS II. METHODS: We hypothesized that residual plasma IDS activity is related to clinical phenotype. We classified 43 Hunter syndrome patients as having attenuated or severe disease types based on clinical characteristics, especially intellectual and cognitive status. There were 27 patients with the severe type and 16 with the attenuated type. Plasma IDS activity was measured by a fluorometric enzyme assay using 4-methylumbelliferyl-alpha-iduronate 2-sulphate. RESULTS: Plasma IDS activity in patients with the severe type was significantly lower than that in patients with the attenuated type (P=0.006). The optimal cut-off value of plasma IDS activity for distinguishing the severe type from the attenuated type was 0.63 nmol.4 hr-1.mL-1. This value had 88.2% sensitivity, 65.4% specificity, and an area under receiver-operator characteristics (ROC) curve of 0.768 (ROC curve analysis; P=0.003). CONCLUSION: These results show that the mild phenotype may be related to residual lysosomal enzyme activity.
Enzyme Assays ; Fibroblasts ; Humans ; Iduronate Sulfatase ; Leukocytes ; Mucopolysaccharidoses ; Mucopolysaccharidosis II ; Phenotype ; Plasma ; Sensitivity and Specificity ; Skin

PURPOSE: Mucopolysaccharidosis type II (MPS II or Hunter syndrome) is a rare lysosomal storage disorder caused by iduronate-2-sulfatase (IDS) deficiency. MPS II causes a wide phenotypic spectrum of symptoms ranging from mild to severe. IDS activity, which is measured in leukocyte pellets or fibroblasts, was reported to be related to clinical phenotype by Sukegawa-Hayasaka et al. Measurement of residual plasma IDS activity using a fluorometric assay is simpler than conventional measurements using skin fibroblasts or peripheral blood mononuclear cells. This is the first study to describe the relationship between plasma IDS activity and clinical phenotype of MPS II. METHODS: We hypothesized that residual plasma IDS activity is related to clinical phenotype. We classified 43 Hunter syndrome patients as having attenuated or severe disease types based on clinical characteristics, especially intellectual and cognitive status. There were 27 patients with the severe type and 16 with the attenuated type. Plasma IDS activity was measured by a fluorometric enzyme assay using 4-methylumbelliferyl-alpha-iduronate 2-sulphate. RESULTS: Plasma IDS activity in patients with the severe type was significantly lower than that in patients with the attenuated type (P=0.006). The optimal cut-off value of plasma IDS activity for distinguishing the severe type from the attenuated type was 0.63 nmol.4 hr-1.mL-1. This value had 88.2% sensitivity, 65.4% specificity, and an area under receiver-operator characteristics (ROC) curve of 0.768 (ROC curve analysis; P=0.003). CONCLUSION: These results show that the mild phenotype may be related to residual lysosomal enzyme activity.
Enzyme Assays ; Fibroblasts ; Humans ; Iduronate Sulfatase ; Leukocytes ; Mucopolysaccharidoses ; Mucopolysaccharidosis II ; Phenotype ; Plasma ; Sensitivity and Specificity ; Skin

OBJECTIVETo identify the mutations of iduronate-2-sulfatase (IDS) gene in mucopolysaccharidosis type II patients.

METHODSPCR-SSCP analysis was applied to detect the common mutations in the exons 2, 3, 5, 7, 8, 9 in IDS-gene of the patient. DNA sequencing and PCR-RFLP were applied to analyze the mutation detected by PCR-SSCP.

RESULTSA new mutation(1253G-->T) of exon 7 of the IDS gene was found by PCR-SSCP and DNA sequencing in the patient, The PCR-restriction enzyme digestion showed that enzyme digestion location appeared in the patient and his mother, which verified the results of sequencing analysis.

CONCLUSIONThe mutation of patient with MPSII could be detected effectively and quickly by the applications of PCR-SSCP, DNA sequencing and PCR-restriction enzyme digestion analysis, and the new mutation thus detected is necessary for the prenatal diagnosis of the pedigree.

Child ; Humans ; Iduronate Sulfatase ; genetics ; Male ; Mucopolysaccharidosis II ; genetics ; Mutation ; Polymorphism, Single-Stranded Conformational

OBJECTIVEWith the emergence of enzyme replacement therapy and progress in bone marrow transplantation, treatment of mucopolysaccharidosis (MPS) is much more promising than ever. In order to benefit from these therapies, determination of the defective enzyme is the prerequisite for any individual patient. To make definite diagnosis for patients suspected of having MPS clinically, the authors established six lysosomal enzymatic assays for leucocytes, including alpha-L-iduronidase, iduronate-2-sulfatase, N-acetylgalactosamine 6-sulfatase, beta-galactosidase, arylsulfatase B, beta-glucuronidase, which are the corresponding enzymes of type I, type II, type IVA, type IVB, type VI, and type VII, respectively.

METHODSeventy patients suspected of having MPS were enrolled from outpatient clinics of the Department of Pediatric Endocrinologic, Genetic and Metabolic Diseases in Xinhua Hospital. Their ages spanned from 10 months to 25 years with the average age 5.7 years. Of them 49 were male and 21 were female. Leukocytes were isolated with Dextran from peripheral blood of suspected patients. Activity of leukocyte alpha-L-iduronidase, iduronate-2-sulfatase, N-acetylgalactosamine 6-sulfatase, beta-galactosidase, beta-glucuronidase were measured using their specific artificial fluorescent substrates, while arylsulfatase B were determined by colorimetric assay with dipotassium 2-hydroxy-5-nitrophenyl sulfate as the substrate.

RESULTOf the 70 clinically suspected cases totally 47 were confirmed of having mucopolysaccharidosis, of whom 7 cases were type I, 28 cases type II, 12 cases type IVA. These data show that type II is the predominant form of MPS in China, succeeded by MPS type IVA. It was also noted that type II has the most variable clinical manifestations and 8 out of 12 type IVA patients had the unique lax joints.

CONCLUSIONThe present study suggest that type II might be the predominant form of MPS cases in China, followed by type IVA and type I.

Adolescent ; Adult ; Child ; Child, Preschool ; Female ; Humans ; Iduronate Sulfatase ; metabolism ; Infant ; Infant, Newborn ; Male ; Mucopolysaccharidoses ; classification ; diagnosis ; enzymology ; Young Adult

Glycogen storage disease (GSD) and mucopolysaccharidosis (MPS) are both independently inherited disorders. GSD is a member of a group of genetic disorders involving enzymes responsible for the synthesis and degradation of glycogen. GSD leads to abnormal tissue concentrations of glycogen, primarily in the liver, muscle, or both. MPS is a member of a group of inherited lysosomal storage diseases, which result from a deficiency in specific enzymatic activities and the accumulation of partially degraded acid mucopolysaccharides. A case of a 16-month-old boy who presented with hepatomegaly is reported. The liver was four finger-breadth-palpable. A laboratory study showed slightly increased serum AST and ALT levels. The liver biopsy showed microscopic features compatible with GSD. The liver glycogen content was 9.3% which was increased in comparison with the reference limit, but the glucose-6-phosphatase activity was within the normal limit. These findings suggested GSD other than type I. Bony abnormalities on skeletal radiographs, including an anterior beak and hook-shaped vertebrae, were seen. The mucopolysaccharide concentration in the urine was increased and the plasma iduronate sulfatase activity was low, which fulfilled the diagnosis criteria for Hunter syndrome (MPS type II). To the best of the authors' knowledge, this is the first case of GSD and Hunter syndrome being identified at the same time.
Animals ; Beak ; Biopsy ; Glucose-6-Phosphatase ; Glycogen ; Glycogen Storage Disease ; Glycosaminoglycans ; Hepatomegaly ; Humans ; Iduronate Sulfatase ; Infant ; Liver ; Liver Glycogen ; Lysosomal Storage Diseases ; Mucopolysaccharidoses ; Mucopolysaccharidosis II ; Muscles ; Plasma ; Spine

OBJECTIVETo identify the mutations of iduronate-2-sulfatase (IDS) gene, and to establish a basis of prenatal gene diagnosis of Hunter syndrome.

METHODSUrine glycosaminoglycan (GAG) assay was used to preliminary diagnosis of mucopolysaccharidosis. PCR-denaturing high-performance liquidchromatograptly (PCR-DHPLC) analysis was performed to detect the mutation in exons 9, 3, 8 of the IDS gene. DNA sequencing was applied to analyze the mutation detected by PCR-DHPLC.

RESULTSAbnormal peaks were found by PCR-DHPLC. A new frame-mutation (1569+TT) in exon 9 of IDS gene was identified by DNA sequencing. Two "T"q inserted in position 1569 base pair (1569+TT) caused a substitution of codon 482 (TTA, leucine) to 482 (TTT, phenylalanine). The "TT" insertion results in the decrease of amino acids from 550 to 482. The patient is a hemizygote and his mother is a heterozygote.

CONCLUSIONA new frame-shift mutation of IDS gene is found to report. The mutation (1569+TT) results in 68 amino acids lost. Probably it causes the enzyme activity seriously dropped down and being pathologically the basis of disease.

Child, Preschool ; Chromatography, High Pressure Liquid ; DNA Mutational Analysis ; Humans ; Iduronate Sulfatase ; genetics ; Male ; Molecular Sequence Data ; Mucopolysaccharidoses ; genetics ; Mucopolysaccharidosis II ; enzymology ; genetics ; Mutation

PURPOSE: Mucopolysaccharidosis II (MPS II) is a lysosomal storage disorder caused by a deficiency of iduronate-2 sulfatase (IdS), which is involved in the degradation of glycosaminoglycan (GAG). In this study, the frequency of fasting hypoglycemia in patients with MPS II was investigated and changes in accumulation of glycogen and GAG in the hepatocytes of IdS-knockout (KO) mice were evaluated before and after recombinant IdS enzyme replacement therapy (ERT). MATERIALS AND METHODS: Plasma glucose levels were evaluated after an 8-hour fast in 50 patients with MPS II. The IdS-KO mice were divided into three groups (group 2; saline, group 3; 0.15 mg/kg of IdS, and group 4; 0.5 mg/kg of IdS); wild-type mice were included as controls (group 1). ERT was initiated intravenously at four weeks of age, and continued every week until 20 weeks of age. RESULTS: The mean glucose level after an 8-hour fast was 94.1 +/- 23.7 mg/dL in the patients with MPS II. Two (4%) out of 50 patients had fasting hypoglycemia. For the mice, GAG in the lysosomes nearly disappeared and glycogen particles in the cytoplasm were restored to the normal range in group 4. CONCLUSION: Glucose metabolism in patients with MPS II appeared to function well despite hepatocytic GAG accumulation and hypothetical glycogen depletion. A higher dose of IdS infusion in MPS II mice led to disappearance of lysosomal GAG and restoration of glycogen to the cytoplasm of hepatocytes.
Animals ; Blood Glucose/analysis ; Enzyme Replacement Therapy/methods ; Glycogen/*analysis ; Glycosaminoglycans/*analysis ; Hepatocytes/chemistry/*enzymology ; Humans ; Hypoglycemia/enzymology/physiopathology ; Iduronate Sulfatase/genetics/*physiology ; Liver/ultrastructure ; Mice ; Mice, Knockout ; Microscopy, Electron ; Mucopolysaccharidosis II/blood/enzymology/physiopathology

Hunter syndrome (or mucopolysaccharidosis type II [MPS II]) arises because of a deficiency in the lysosomal enzyme iduronate-2-sulfatase. Short stature is a prominent and consistent feature in MPS II. Enzyme replacement therapy (ERT) with idursulfase (Elaprase(R)) or idursulfase beta (Hunterase(R)) have been developed for these patients. The effect of ERT on the growth of Korean patients with Hunter syndrome was evaluated at a single center. This study comprised 32 patients, who had received ERT for at least 2 yr; they were divided into three groups according to their ages at the start of ERT: group 1 (<6 yr, n=14), group 2 (6-10 yr, n=11), and group 3 (10-20 yr, n=7). The patients showed marked growth retardation as they got older. ERT may have less effect on the growth of patients with the severe form of Hunter syndrome. The height z-scores in groups 2 and 3 revealed a significant change (the estimated slopes before and after the treatment were -0.047 and -0.007, respectively: difference in the slope, 0.04; P<0.001). Growth in response to ERT could be an important treatment outcome or an endpoint for future studies.
Adolescent ; Body Height ; Child ; Child, Preschool ; Demography ; Enzyme Replacement Therapy ; Humans ; Iduronate Sulfatase/*therapeutic use ; Infant ; Male ; Mild Cognitive Impairment/etiology ; Mucopolysaccharidosis II/complications/diagnosis/*therapy ; Mutation ; Phenotype ; Protein Isoforms/therapeutic use ; Republic of Korea ; Young Adult

OBJECTIVETo investigate and establish the gene diagnosis methods for the frequent mutations of iduronate-2-sulphatase(IDS) gene in mucopolysaccharidosis type II patients.

METHODSpolymerase chain- reaction-single strand conformation polymorphism PCR-SSCP) analysis was applied to detect the mutations of exons 3, 8 and 9 which were hot spots in the iduronate-2-sulfatase gene; DNA sequencing was applied to analyze the mutations which had been detected by PCR-SSCP; PCR-restriction fragment length polymorphism (PCR-RFLP) was applied to detect the results of DNA sequencing.

RESULTSObvious and abnormal bands in exon 9 of the IDS gene were found by applying PCR-SSCP; the mutation(C1672T) of exon 9 was found in the patient through DNA sequencing, which led to amino acid replacement(R468W); the PCR-restriction enzyme digestion showed that only one band(554 bp) appeared in the patient, but there were two bands (257 bp and 297 bp) in his parents, and it verified the results of sequencing analysis.

CONCLUSIONPCR-SSCP analysis, DNA sequencing analysis and PCR-restriction enzyme digestion are effective methods for MPS II diagnosis. Combined applications of these methods can verify and complement each other and improve the accuracy of diagnosis.

Amino Acid Substitution ; Base Sequence ; Child ; China ; Codon, Nonsense ; DNA ; chemistry ; genetics ; DNA Mutational Analysis ; Humans ; Iduronate Sulfatase ; genetics ; Male ; Mucopolysaccharidosis II ; enzymology ; genetics ; Mutation ; Point Mutation ; Polymorphism, Single-Stranded Conformational

OBJECTIVETo detect potential mutation of iduronate-2-sulfatase (IDS) gene in a family affected with mucopolysaccharidosis type Ⅱ (MPS Ⅱ).

METHODSFor the proband and his unaffected mother, the whole coding sequence of the IDS gene was analyzed with PCR and bidirectional Sanger sequencing.

RESULTSA novel splicing mutation, c.709-1G>A, was detected in the proband, for which his mother was heterozygous.

CONCLUSIONThe c.709-1G>A splicing mutation of the IDS gene is probably causative for the MSP Ⅱ in the proband. Prenatal diagnosis for the mutation may avoid birth of further child affected with this disease.

Base Sequence ; Child ; DNA Mutational Analysis ; methods ; Family Health ; Female ; Genetic Predisposition to Disease ; genetics ; Glycoproteins ; genetics ; metabolism ; Heterozygote ; Humans ; Iduronate Sulfatase ; genetics ; metabolism ; Male ; Mothers ; Mucopolysaccharidosis II ; diagnosis ; enzymology ; genetics ; Mutation