• Journal of mucopolysaccharidosis and rare diseases
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• v.2 no.1
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• pp.31-31
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• 2016

Purpose: To describle clinical features and enzyme activity of Vietnamese patients with Mucolipidosis type II. Methods: Clinical features, laboratory and plasma lysosom enzyme activity by 4 MU-Fluorometric assay was studied from 2014-2015 at the Northern referral center of Pediatrics - National Children's Hospital. Results: 16 cases (7 girls and 9 boys) were diagnosed with I-cell bases on clinical symptoms and enzyme activities studies. Diagnosis age was $5.93{\pm}4.28$ years, onset age was recognised from birth to 4 years (median 1.25) with the feature of joint stiffness and bone deformation. All cases presented with the feature of joint stiffness, chest deformation and kyphoscoliosis; Fifteen cases (93.7%) had coarse facial features. No patients had hepatosplenomegaly on abdominal ultrasound, 5/15 patients had heart valves disease. Enzyme assay showed ${\alpha}$-Hexosaminidase of $1,885.9{\pm}338.7$ (nmol/mg plasma/17 hrs), ${\alpha}$-Iduronate sulfatase of $4,534.8{\pm}1,062.9nmol/mg$ plasma/4 hrs). Conclusion: Mucolipidosis II seriously affected the life of the patients with skeletal deformities, contractures develop in all joints and cardiac involvement.

• Korean Journal of Audiology
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• v.25 no.1
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• pp.49-54
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• 2021

Type II mucopolysaccharidosis (MPS II) commonly known as Hunter syndrome, is a rare X-linked lysosomal storage disorder caused by iduronate-2-sulfatase deficiency, which in turn causes otorhinolaryngological manifestations, including sensorineural hearing loss (SNHL). Previously, the median survival age of patients with MPS was approximately 13.4 years. However, in the era of enzyme replacement therapy and other multidisciplinary care modalities, the life expectancy has increased. Herein, we report a rare case of an adolescent with MPS II who underwent SNHL treatment with cochlear implantation (CI). Based on unexpected findings of mastoid emissary veins and overgrowth of the vessels around the temporal bone, CI was performed using the transmeatal approach instead of the conventional transmastoid method, to avoid damage to the vessels. The average hearing threshold after CI was 35 dB and no surgical complications were encountered. Adolescent MPS II may present vessel abnormalities, which can reduce the success rate of surgery. In patients with MPS II with SNHL, CI should be performed under careful monitoring of vessel overgrowth. Moreover, with regard to feasibility of CI in adolescent patients with MPS II with SNHL, surgical techniques such as the transmeatal approach should be selected based on adequate assessment of the case.

• Journal of Audiology & Otology
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• v.25 no.1
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• pp.49-54
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• 2021

Type II mucopolysaccharidosis (MPS II) commonly known as Hunter syndrome, is a rare X-linked lysosomal storage disorder caused by iduronate-2-sulfatase deficiency, which in turn causes otorhinolaryngological manifestations, including sensorineural hearing loss (SNHL). Previously, the median survival age of patients with MPS was approximately 13.4 years. However, in the era of enzyme replacement therapy and other multidisciplinary care modalities, the life expectancy has increased. Herein, we report a rare case of an adolescent with MPS II who underwent SNHL treatment with cochlear implantation (CI). Based on unexpected findings of mastoid emissary veins and overgrowth of the vessels around the temporal bone, CI was performed using the transmeatal approach instead of the conventional transmastoid method, to avoid damage to the vessels. The average hearing threshold after CI was 35 dB and no surgical complications were encountered. Adolescent MPS II may present vessel abnormalities, which can reduce the success rate of surgery. In patients with MPS II with SNHL, CI should be performed under careful monitoring of vessel overgrowth. Moreover, with regard to feasibility of CI in adolescent patients with MPS II with SNHL, surgical techniques such as the transmeatal approach should be selected based on adequate assessment of the case.

• Journal of mucopolysaccharidosis and rare diseases
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• v.5 no.1
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• pp.17-21
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• 2021

Hunter syndrome or mucopolysaccharidosis type II (MPS-II) (OMIM 309900) is a rare lysosomal storage disorder caused by deficiency in the activity of the enzyme iduronate-2-sulfatase. This enzyme is responsible for the catabolism of the following two different glycosaminoglycans (GAGs): dermatan sulfate and heparan sulfate. The lysosomal accumulation of these GAG molecules results in cell, tissue, and organ dysfunction. Patients can be broadly classified as having one of the following two forms of MPS II: a severe form and an attenuated form. In the severe form of the disease, signs and symptoms (including neurological impairment) develop in early childhood, whereas in the attenuated form, signs and symptoms develop in adolescence or early adulthood, and patients do not experience significant cognitive impairment. The involvement of the skeletal-muscle system is because of essential accumulated GAGs in joints and connective tissue. MPS II has many clinical features and includes two recognized clinical entities (mild and severe) that represent two ends of a wide spectrum of clinical severities. However, enzyme replacement therapy is likely to have only a limited impact on bone and joint disease based on the results of MPS II studies. The aim of this study was to review the involvement of joints in MPS II.

• Clinical and Experimental Pediatrics
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• v.51 no.6
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• pp.650-654
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• 2008

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.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.18 no.2
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• pp.62-67
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• 2018

Hunter syndrome, also known as mucopolysaccharidosis Type II (MPS II), is one of the lysosomal storage diseases caused by a lack of the enzyme iduronate 2-sulfatase (I2S). Lack of the I2S enzyme activity leads to accumulation of the glycosaminoglycans (GAG), causing dysfunction of multiple organs and systems. MPS II is an X-linked recessive disease due to mutation of IDS gene located on long arm of the X chromosome (Xq28). To date, more than 350 mutations of IDS gene have been identified in Hunter syndrome. Phenotypes of MPS II are classified as either severe or attenuated depending on the degree of cognitive impairment. Because the phenotype of MPS II is related to the type of mutation, identifying mutations is useful in predicting prognosis. We recently had a case of MPS II diagnosed by exome sequencing in a 7 month old boy with infantile spasm uncontrolled by AED. He was diagnosed with hearing loss at 2 months of age, and he took vigabatrin and prednisolone to control infantile spasms diagnosed at 3 months of age. At 6 months of age, whole exome sequencing was performed to evaluate the infantile spasm and hearing loss in this patient, and the mutation c.851C>T (p.Pro284Leu) inherited from hemizygous mother was revealed. The results of urine Cetylpyridinium Chloride (CPC) precipitation test, which were negative until 8 months of age, were positive from 9 months of age. We report a case of MPS II diagnosed by exome sequencing and treated through enzyme replacement therapy from 9 months after birth.