• Journal of mucopolysaccharidosis and rare diseases
• /
• v.2 no.1
• /
• pp.1-4
• /
• 2016

Mucolipidosis type II (MLII; MIM#252500) and type III alpha/beta (MLIIIA; MIM#252600) very rare lysosomal storage disease cause by reduced enzyme activity of GlcNAc-1-phosphotransferase. ML II is caused by a total or near total loss of GlcNAc-1-phosphotransferase activity whether enzymatic activity in patient with ML IIIA is reduced. While ML II and ML III share similar clinical features, including skeletal abnormalities, ML II is the more severe in terms of phenotype. ML III is a much milder disorder, being characterized by latter onset of clinical symptoms and slower progressive course. GlcNAc-1-phosphotransferase is encoded by two genes, GNPTAB and GNPTG, mutations in GNPTAB give rise to ML II or ML IIIA. To date, more than 100 different GNPTAB mutations have been reported, causing either ML II or ML IIIA. Despite development of new diagnostic approach and understanding of disease mechanism, there is no specific treatment available for patients with ML II and ML IIIA yet, only supportive and symptomatic treatment is indicated.

• Journal of mucopolysaccharidosis and rare diseases
• /
• v.2 no.1
• /
• pp.8-12
• /
• 2016

Mucolipidosis (ML) is a kind of skeletal dysplasia. Characteristic X-ray findings of the bone may contribute to the early diagnosis and treatment of ML II/III. Skeletal radiographs show distinctive patterns at different ages: neonatal hyperparathyroidism, osteodystrophy (similar to chronic osteitis fibrosa cystica), and dysostosis multiplex. Patients with ML II/III show a mixture of osteodystrophic bone changes and atypical changes of dysostosis multiplex: proximal pointing of the metacarpals in the wrist, dysplastic changes in the lower third of the ilia, marked broadening of the ribs becoming oar-shaped, and beaking of the lower thoracic and lumbar vertebrae. In ML II, the osteodystrophy has clinical and radiographic features of neonatal hyperparathyroidism. In some neonatal subjects, chemical hyperparathyroidism is also demonstrated. After transient hyperparathyroidism in newborns, the progressive osteitis fibrosa cystica develops from 3-6 months of age. Patients with ML III show prominent skeletal involvement, particularly the destruction of vertebral bodies and the femoral heads. Intravenous pamidronate treatment is well tolerated, and it can produce clinical effects, with a reduction in bone pain and improvements in mobility in patients with ML III. In this review, the skeletal manifestations of ML II and III are investigated.

• Journal of mucopolysaccharidosis and rare diseases
• /
• v.2 no.1
• /
• pp.13-16
• /
• 2016

Mucolipidosis (ML) II/III are autosomal recessive diseases caused by deficiency of post-translational modification of lysosomal enzymes. The mannose-6-phosphate (M6P) residue in lysosomal enzymes synthesized by N-acetylglucosamine 1-phosphotransferase (GlcNAc-phosphotransferase) serves as recognition marker for trafficking in lysosomes. GlcNAc-phosphotransferase is encoded by GNPTAB and GNPTG. Mutations in GNPTAB cause severe ML II alpha/beta and the attenuated ML III alpha/beta. Whereas mutations in GNPTG cause the ML III gamma, the attenuated type of ML III variant. For the diagnostic approaches, increased urinary oligosaccharides excretion could be a screening test in clinically suspicious patients. To confirm the diagnosis, instead of measuring the activity of GlcNAc phosphotransferase, measuring the enzymatic activities of different lysosomal hydrolases are useful for diagnosis. The activities of several lysosomal hydrolases are decreased in fibroblasts but increased in serum of the patients. In addition, the sequence analysis of causative gene is warranted. Therefore, the confirmatory diagnosis requires a combination of clinical evaluation, biochemical and molecular genetic testing. ML II/III show complex disease manifestations with lysosomal storage as the prime cellular defect that initiates consequential organic dysfunctions. As there are no specific therapy for ML to date, understanding the molecular pathogenesis can contribute to develop new therapeutic approaches ultimately.

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

• Journal of The Korean Society of Inherited Metabolic disease
• /
• v.5 no.1
• /
• pp.65-75
• /
• 2005

Purpose: To understand genetic differences and similarities between mucolipidosis and control. Methods: Using the fibroblast of the mucolipidosis II and control, forward and reverse subtracted libraries were constructed. Among these clones, we investigated mutations in the GNPTA (MGC4170) gene, which codes for the ${\alpha}/{\beta}$ subunits of phosphotransferase, and in the GNPTAG gene, which codes for the ${\gamma}$ subunits in 5 Korean patients with mucolipidosis type II or IIIA. Result: Several differentially expressed cDNAs were cloned and their sequences were determined. Mutation analysis of the interested gene, GNPTA was performed and we identified 7 mutations in the GNPTA gene, but none in the GNPTAG gene. The mutations in type II patients included p.Q104X(c.310C>T), p.R1189X(c.3565C>T), p.S1058X(c.3173C>G), p.W894X(c.2681G>A) and p.H1158fsX15(c.3474_3475delTA), all of which are non-sense or frame shift mutations. However, a splicing site mutation, IVS13+1G>A (c.2715+1G>A) was detected along with a non-sense or a frame shift mutation (p.R1189X or p.E858fsX3(c.2574_2575delGA)) in two mucolipidosis type IIIA patients. Conclusion: This report shows that mutations in the GNPTA gene coding for the ${\alpha}{\beta}$subunits of phosphotransferase, and not mutations in the GNPTAG gene, account for most of mutations found in Korean patients with mucolipidosis type II or IIIA.

• Journal of mucopolysaccharidosis and rare diseases
• /
• v.2 no.1
• /
• pp.19-22
• /
• 2016

Purpose: Mucolipidosis type II (ML II), also known as I-cell disease is an autosomal recessive inherited disorder of lysosomal enzyme transport caused by a deficiency of the uridine diphosphate (UDP)-N-acetylglucosamine:lysosomal enzyme N-acetylglucosamine-1-phosphotransferase (GlcNAc-phosphotransferase). Clinical manifestations are skeletal abnormalities, mental retardation, cardiac disease, and respiratory complications. A severely and rapidity progressive clinical course leads to death before 10 years of age. Methods/Results: In this study we diagnosed three cases of prenatal ML II in two different at-risk families. We compared two procedures -biochemical analysis and molecular analysis - for the prenatal diagnosis of ML II. Both methods require an invasive procedure to obtain specimens for the diagnosis. Biochemical analysis requires obtaining cell cultures from amniotic fluid for more than two weeks, and would result in a late diagnosis at 19 to 22 weeks of gestation. Molecular genetic testing by direct sequence analysis is usually possible when mutations are confirmed in the proband. Molecular analysis has an advantage in that it can be performed during the first-trimester. Conclusion: Molecular diagnosis is a preferable method when a prompt decision is necessary.

• Journal of mucopolysaccharidosis and rare diseases
• /
• v.2 no.1
• /
• pp.28-28
• /
• 2016

• Journal of mucopolysaccharidosis and rare diseases
• /
• v.2 no.1
• /
• pp.29-30
• /
• 2016

• Clinical and Experimental Pediatrics
• /
• v.55 no.11
• /
• pp.438-444
• /
• 2012

Mucolipidosis II (ML II) or inclusion cell disease (I-cell disease) is a rarely occurring autosomal recessive lysosomal enzyme-targeting disease. This disease is usually found to occur in individuals aged between 6 and 12 months, with a clinical phenotype resembling that of Hurler syndrome and radiological findings resembling those of dysostosis multiplex. However, we encountered a rare case of an infant with ML II who presented with prenatal skeletal dysplasia and typical clinical features of severe secondary hyperparathyroidism at birth. A female infant was born at $37^{+1}$ weeks of gestation with a birth weight of 1,690 g (<3rd percentile). Prenatal ultrasonographic findings revealed intrauterine growth retardation and skeletal dysplasia. At birth, the patient had characteristic features of ML II, and skeletal radiographs revealed dysostosis multiplex, similar to rickets. In addition, the patient had high levels of alkaline phosphatase and parathyroid hormone, consistent with severe secondary neonatal hyperparathyroidism. The activities of ${\beta}$-D-hexosaminidase and ${\alpha}$-N-acetylglucosaminidase were moderately decreased in the leukocytes but were 5- to 10-fold higher in the plasma. Examination of a placental biopsy specimen showed foamy vacuolar changes in trophoblasts and syncytiotrophoblasts. The diagnosis of ML II was confirmed via GNPTAB genetic testing, which revealed compound heterozygosity of c.3091C>T (p.Arg1031X) and c.3456_3459dupCAAC (p.Ile1154GlnfsX3), the latter being a novel mutation. The infant was treated with vitamin D supplements but expired because of asphyxia at the age of 2 months.

• Journal of The Korean Society of Inherited Metabolic disease
• /
• v.17 no.3
• /
• pp.85-91
• /
• 2017

Purpose: The aim of this study was to describe the clinical and biochemical features as well as the molecular analysis of a newly diagnosed illustrative case with ML II and to analyze the clinical features of 11 Korean patients with ML II/III. Method: Including a newly diagnosed patient, total 11 patients in 10 families were diagnosed as ML II (n=7) or ML III (n=4) were enrolled in the study. A diagnosis of ML II or III was made by demonstrating increased lysosomal enzyme activities in the plasma and sequence analysis of GNPTAB with characteristic clinical features. Result: A illustrative case of ML II patient was a 17 month-old boy showing characteristic facial appearance, multiple joint contractures with cardiac involvements. The enzyme assay showed increased lysosomal enzyme activities in the plasma. We identified compound heterozygous mutations in GNPTAB sequence analysis, including a frameshift (c.3428dupA [pAsn1143Lysfs*3]) and a nonsense variant c.673C>T (p.Gln225*). In total 11 patients with ML II/III, the patients with ML II showed severe growth retardation (height standard deviation score -3.2 [${\pm}1.5$]), compare to patients with ML III. Furthermore, patients with ML II patients had serious cardiac problem (n=4), hepatomegaly (n=3) and underwent tracheostomy (n=3) with further respiratory support due to respiratory distress. To improve osteoporosis and bone pain, all patients with ML III and four of 7 patients with ML II treated with intravenous pamidronate. Conclusion: Here we showed a newly diagnosed case of ML II and clinical features of 11 Korean patients with ML II or III. These data could be helpful for further diagnosis of mucolipidosis, a rare inherited metabolic disease, in Korea.