• Journal of Genetic Medicine
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• v.5 no.1
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• pp.21-25
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• 2008

Purpose : In recent years, many countries have adopted newborn screening programs that use tandem mass spectrometry (MS/MS) to screen and the number of diseases screened has also increased. We began screening for inherited metabolic disorders using MS/MS in April, 2001. Our goal was to determine the overall prevalence of metabolic disorders and to assess the effectiveness of newborn screening by MS/MS in Korea. Methods : From April, 2001 to December, 2007, we screened newborns and high risk groups using MS/MS. Acylcarnitines and amino acids were extracted and butylated and were introduced into the inlet of MS/MS. Confirmatory testing including a repeat newborn screening, and urine organic acid and plasma amino acid analysis were performed on a case-by-case basis. Results : The total number of screened subjects 284,933 which comprised 251,799 neonates and 33,134 high risk subjects. The recall rate was 0.4% (1158 tests) and true positive cases were 117 (0.04%). Confirmed metabolic disorders (newborn/high risk group) were as follows; 78 (25/53) amino acid disorders, 27 (16/11) organic acid disorders, and 12 (5/7) fatty acid oxidation disorders. The estimated prevalence of inherited metabolic diseases in newborns was 1:5,000 and that in the total group was 1:2,000. Conclusion : Newborn screening by MS/MS improved the detection of many inherited metabolic disorders. We therefore propose that all newborns be screened by a MS/MS national program and followed-up using a systemic organization strategy.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.6 no.1
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• pp.58-62
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• 2006

Gaucher disease is an inherited disorder due to a deficiency in the activity of glucocerebrosidase (EC. 3.2.1.45) by genetic mutation which resulted from missense, nonsense, frameshift, deletion in long arm 21 of chromosome 1 (1q21). Gaucher disease is classified into the main three types as type 1 (nonneuronopathic), type 2 (acute neuronopathic) and type 3 (subacute neuronopathic) according to the progressive phase of manifestations and nervous system involvement. Gaucher disease patients had been treated by using the method as splenectomy and bone marrow transplantation. But enzyme replacement therapy as a more effective treatment has been available since the early 1990's. In order to treat Gaucher disease efficiently by using ERT, it is necessary to chase the progress of the therapy. In this study, therefore, we tried to chase the progress of the ERT by using the measurement of chitotriosidase activity in Gaucher disease patients.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.18 no.2
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• pp.50-54
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• 2018

Jehovah's Witnesses do not accept blood transfusions, because of their particular interpretation of the Old and New Testaments. When people with such religious convictions are in need of medical care, their faith and belief may become an obstacle for proper treatment, and pose legal, ethical, and medical challenges for the health care providers. We report two inherited metabolic disorder cases in South Korea where the infants died whilst under medical care because of parental refusal of blood transfusions for religious reasons. Case 1 had methylmalonic acidemia, Down syndrome and associated congenital cardiac anomalies requiring surgery. Case 2 had anemia and methylmalonic acidemia requiring dialysis to treat hyperammonemia and metabolic acidosis. For effective medical management, they needed life-saving blood transfusions. As a part of alternative treatment, Erythropoietin was administered in both cases. As a result, two babies died from their extremely low hemoglobin and hematocrit. The hemoglobin concentrations below 2.7 g/dL without cardiac problem and 5.4 g/dL with cardiac anomaly complicated by pulmonary hypertension are considered life-threatening hemoglobin threshold. The medical professional must respect and accommodate religious beliefs of the patients who can make informed decisions. However, when parents or legal guardians oppose medical treatment of their babies and incompetent care receivers on cultural and religious grounds, the duty to assist and save persons exposed to serious danger, particularly life-threatening events must come first.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.5 no.1
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• pp.18-22
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• 2005

Pompe disease is a genetic disorder caused by a deficiency of acid ${\alpha}$-glucosidase (GAA). This enzyme defect results in lysosomal glycogen accumulation in multiple tissues and cell types, with cardiac, skeletal, and smooth muscle cells the most seriously affected. Infantile-onset Pompe disease is uniformly lethal. Affected infants present in the first few months of life with hypotonia, generalized muscle weakness, and a hypertrophic cardiomyopathy, followed by death from cardiorespiratory failure or respiratory infection, usually by 1 year of age. Late-onset forms is characterized by a lack of severe cardiac involvement and a less severe short-term prognosis. Enzyme replacement therapy for Pompe disease is intended to address directly the underlying metabolic defect via intravenous infusions of recombinant human GAA to provide the missing enzyme. We experienced one case of Pompe disease in 3-years old boy that has improved his exercise ability and cardiac function after GAA enzyme replacement therapy.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.5 no.1
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• pp.9-17
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• 2005

Homocystinuria is a metabolic disorder caused by a deficiency of cystathionine ${\beta}$-synthase (CBS). Patients with homocystinuria show clinical symptoms such as mental retardation, lens dislocation, vascular disease with life-threatening thromboembolisms and skeletal deformities. Generally, the major treatments for CBS deficiency include pharmacologic doses of pyridoxine or dietary restriction of methionine. However, there is no effective treatment for this disease up till today and gene therapy can be an attractive novel approach to treatment of the disease. We investigated whether a recombinant adeno-associated virus could be used as a CBS gene transfer vector to reduce the excessive homocysteine level in the homocystinuria mouse model. Recombinant adeno-associated virus vector encoding the human CBS gene (rAAV-hCBS), driven by EF1-a promoter, was infused into CBS-deficient mice ($CBS^{-/-}$) via intramuscular (IM) and intraperitoneal (IP) injection. IP injection was more efficient than IM injection for prolongation of lives and reduction of plasma homocysteine levels. After 2 weeks of gene transfer by IP injection, serum homocysteine level was significantly decreased in treated mice compared with the age-matched controls and the life span was extended about 1.5 times. Also, increased expression of CBS gene was observed by immunohistochemical staining in livers of treated $CBS^{-/-}$ mice and microvesicular lipid droplets was decreased in cytoplasm of liver. These results demonstrate the possibility and efficacy of gene therapy by AAV gene transfer in homocystinuria mice.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.16 no.2
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• pp.57-61
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• 2016

Isovaleric acidemia (IVA) is an autosomal recessively inherited organic acid disorder due to a defect of the enzyme isovaleryl-CoA dehydrogenase in the leucine metabolic pathway. Deficiency of this enzyme results in the accumulation of derivatives of isovaleryl-CoA. In acute illness in IVA, isovaleric acid and its derivatives accumulate and profound metabolic acidosis with ketosis, characteristic pungent body odor, hypoglycemia, and hyperammonemia can be developed. Additionally, recurrent vomiting, failure to thrive, developmental delay, epilepsy and mental retardation are chronic presenting symptoms and signs for IVA. On the result of newborn screening for inherited metabolic disorders, increased levels of isovalerylcarnitine (C5) are shown. However, C5 elevation can be accompanied with short/branched-chain acyl-CoA dehydrogenase (SBCAD) and therapy with certain antibiotics containing pivalic acid. Quantitative measurement of organic acids in urine and acylcarnitine profiles in plasma are necessary to differential diagnosis. Molecular genetic analysis of the IVD gene for IVA and ACADSB is also helpful to confirm IVA and SBCAD deficiency, respectively. Considering that IVA can be associated with significant morbidity and mortality at acute presentation of metabolic crisis, early diagnosis prior to the onset of symptoms by newborn screening enable to introduction of early treatment and prevention of acute and chronic complications.

• Journal of Genetic Medicine
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• v.19 no.2
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• pp.94-99
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• 2022

Lesch-Nyhan disease (LND) is a rare X-linked recessive inherited purine metabolic disorder that accompanies neurodevelopmental problems. Neurofibromatosis type 1 (NF1) is a relatively common autosomal dominant inherited genetic disorder characterized by tumors in various systems. Some children with NF1 also accompanies neurodevelopmental problems. Here, we describe a 5-year-old boy with a maternally inherited pathogenic variant in NF1 and hypoxanthine-guanine phosphoribosyltransferase (HPRT). He was referred for severe neurodevelopmental impairment and hyperuricemia. His mother was diagnosed with NF1 and the patient was also suspected of having NF1 because of cafe au lait macules. He had dystonia, rigidity, cognitive deficit, and speech/language impairment. Serum and urine uric acid concentrations were elevated. He had more severe neurodevelopmental delay than patients with only NF1, so his clinical symptoms could not be fully understood by the disease alone. To find the cause of his neurologic symptoms and hyperuricemia, the patient and his mother underwent a whole-exome sequencing test. As a result, the pathogenic variant c.151C>T (p.Arg51Ter) in HPRT1 was identified as hemizygote in the patient and heterozygote in his mother. The pathogenic variant c.7682C>G (p.Ser2561Ter) in NF-1 was identified as heterozygotes in both of them. Although the clinical symptoms of both diseases were overlapping and complicated, genetic testing was helpful for accurate diagnosis and treatment. Therefore, we suggest to consider preemptive genetic evaluation if there are symptoms not sufficiently explained by known existing diseases. And it is considered valuable to review this rare case to understand the clinical course and possible synergic effects of these diseases.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.6 no.1
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• pp.32-39
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• 2006

Galactosialidosis is a lysosomal storage disease associated with a combined deficiency of ${\beta}$-galactosidase and ${\alpha}$-neuraminidase, secondary to a defect of another lysosomal protective protein. It is a neurodegenerative disorder clinically characterized by psychomotor deterioration, cerebellar ataxia, coarse facies, generalized bony deformity and organomegaly. Three phenotypic subtype are recognized: early infantile, late infantile and juvenile/adult type. We report a 13 months old boy with a late infantile galactosialidosis. He was presented with progressive mental regression and motor disturbance and observed cherry red spot, hearing loss, moderate dysostosis multiplex and vacuolated lymphocytes in peripheral blood. He showed only ${\beta}$-galactosidase deficiency in the lymphocytes and was initially diagnosed as $GM_1$-gangliosidosis type 1. However, further studies revealed the possible defect of ${\alpha}$-neuraminidase suggesting that he was a case of galactosialidosis which was mimicking $GM_1$-gangliosidosis type 1.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.15 no.3
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• pp.160-164
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• 2015

Hunter syndrome(Mucopolysaccharidosis type II, MPS type II) is an X-linked disorder of glycosaminoglycans (GAGs) metabolism caused by an iduronate-2-sulfatase (IDS2) deficiency. A 24-month-old boy visited the department of pediatrics with the chief compliant of chronic purulent rhinorrhea beginning at age one. He had a history of repeated acute otitis media and chronic rhinitis. On physical examination he had a coarse face, enlarged tongue, distended abdomen, joint stiffness, and Mongolian spots at his first visit. The urine GAGs level was elevated at 66.10 mg/mmolCr (reference range, <11.1) and iduronate-2-sulfatase activity in leukocyte was decreased at 0.21 nmol/mg protein/hr (reference range, 18.7-57). Finally with an IDS gene mutational analysis, recombinant known mutation between intron 7 and distal of exon 3 in IDS2 was detected. Recombinant iduronate-2-sulfatase therapy was started without any infusion related reactions. The author highlights the importance of suspecting Hunter syndrome when pediatric patients visit with chronic purulent rhinorrhea which is a common cause of hospital visits for infants and children.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.13 no.1
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• pp.30-36
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• 2013

6-pyruvoyltetrahydropterin synthase (PTPS) deficiency is autosomal recessive disorder and the most common type of tetrahydrobiopterin (BH4) deficiency. It is caused by deficiency of PTPS, a cofactor involved in the biosynthesis of BH4 from guanosine triphosphate (GTP). Unlike classical phenylketonuria, which needs restriction of dietary phenylalanine for whole life, BH4 deficiency is treated by tetrahydrobiopterin, levodopa, and 5-hydroxytryptophan replacement. So it is important to make accurate diagnosis and initiate treatment as soon as possible for a better prognosis. There is no retrospective study of Korean patients undergoing long-term treatment for PTPS deficiency. We report 9 Korean patients with PTPS deficiency and their laboratory findings including BH4 loading tests, urine pterin tests, genotypes, dihydropteridine reductase (DHPR) activities and clinical manifestations including medication and developmental delay existence.