• Journal of mucopolysaccharidosis and rare diseases
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• v.3 no.1
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• pp.20-27
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• 2017

Purpose: Mucopolysaccharidosis IV (MPS IV) is a disease characterized by deficient activity of N-acetylgalactosamine-6-sulfatase (GALNS) causing excessive lysosomal storage of keratan sulfate (KS). The identification of the relevant disaccharide units of KS after keratanase II digestion followed by liquid chromatography/tandem mass spectrometry detection (LC-MS/MS) is validated and applicable for the preliminary diagnosis of MPS IV. Methods: A total of 67 urine samples were collected and analyzed from 11 MPS IV patients comprising 10 MPS IVA and one MPS IVB patients, and 56 normal controls. Urinary glycosaminoglycan was first precipitated by the Alcian blue method followed by a digestion of keratanase II. The protonated species of the digested disaccharide products were detected by using multiple reaction monitoring experiment. Results: One particular disaccharide of KS was selected. The transition mass-to-charge (m/z) of the parent ion and its daughter ion after collision was $462.0{\rightarrow}97.0$, whereas the chondrosine used as an internal standard in this assay was m/z $353.9{\rightarrow}73.0$. The results corresponded well with the two-dimensional electrophoresis method. The quantities of urinary KS were significantly raised in confirmed MPS IV patients when comparing with those of normal controls ($170.2{\pm}81.1$ vs. $4.06{\pm}1.92{\mu}g/mL$). Conclusion: The LC-MS/MS method for MPS IVA determination is specific, sensitive, validated, and applicable for urinary KS quantification. This method can be used not only as a first-line biochemistry examination of MPS IVA, but also as an outcome survey after enzyme replacement therapy.

• Clinical and Experimental Pediatrics
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• v.55 no.11
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• pp.430-437
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• 2012

Purpose: Mucopolysaccharidosis IVA (MPS IVA; Morquio A syndrome) is rare lysosomal storage disorder caused by N-acetylgalactosamine-6-sulfatase (GALNS) deficiency. Only a few MPS IVA cases have been reported in the Korean literature; there is a paucity of research about clinical or radiologic findings for this disorder. Therefore, we studied clinical findings, radiological features, and genetic data of Korean MPS IVA patients for determining factors that may allow early diagnosis and that may thus improve the patients' quality of life. Method: MPS IVA was confirmed via assay for enzymatic activity of leukocytes in 10 patients. The GALNS gene was analyzed. Patients' charts were retrospectively reviewed for obtaining clinical features and evaluated for radiological skeletal surveys, echocardiography, pulmonary function test, and ophthalmologic test results. Result: Nine patients had severe clinical phenotype, and 1 had an intermediate phenotype, on the basis of clinical phenotype criteria. Radiologic findings indicated skeletal abnormalities in all patients, especially in the hips and extremities. Eight patients had an odontoid hypoplasia, and 1 showed mild atlantoaxial subluxation and cord myelopathy. Genetic analysis indicated 10 different GALNS mutations. Two mutations, c.451C>A and c.1000C>T, account for 37.5% (6/16) and 25% (4/16) of all mutations in this samples, respectively. Conclusion: An understanding of the clinical and radiological features involved in MPS IVA may allow early diagnosis of MPS IVA. Adequate evaluations and therapy in the early stages may improve the quality of life of patients suffering from skeletal abnormalities and may reduce life-threatening effects of atlantoaxial subluxation.

• Journal of Genetic Medicine
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• v.19 no.1
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• pp.32-37
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• 2022

Mucopolysaccharidosis type VI (MPS VI) is an autosomal recessive lysosomal disorder caused by the deficiency of arylsulfatase B due to mutations in the ARSB gene. Here, we report the case of a Korean female with a novel variant of MPS VI. A Korean female aged 5 years and 8 months, who is the only child of a healthy non-consanguineous Korean couple, presented at our hospital for severe short stature. She had a medical history of umbilical hernia and recurrent otitis media. Her symptoms included snoring and mouth breathing. Subtle dysmorphic features, including mild coarse face, joint contracture, hepatomegaly, and limited range of joint motion, were identified. Radiography revealed deformities, suggesting skeletal dysplasia. Growth hormone (GH) provocation tests revealed complete GH deficiency. Targeted exome sequencing revealed compound heterozygous mutations in the ARSB genes c.512G>A (p.Gly171Asp; a pathogenic variant inherited from her father) and c.1157C>T (p.Ser386Phe; a novel variant inherited from her mother in familial genetic testing). Quantitative tests revealed increased urine glycosaminoglycan (GAG) levels and decreased enzyme activity of arylsulfatase B. While on enzyme replacement therapy and GH therapy, her height increased drastically; her coarse face, joint contracture, snoring, and obstructive sleep apnea improved; urine GAG decreased; and left ventricular mass index was remarkably decreased. We report a novel variant-c.1157C>T (p.Ser386Phe)-of the ARSB gene in a patient with MPS VI; these findings will expand our knowledge of its clinical spectrum and molecular mechanisms.