• Journal of Genetic Medicine
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• v.15 no.2
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• pp.87-91
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• 2018

X-linked dominant mutations in lysosome-associated membrane protein 2 (LAMP2) gene have been shown to be the cause of Danon disease, which is a rare disease associated with clinical triad of cardiomyopathy, skeletal myopathy, and mental retardation. Cardiac involvement is a common manifestation and is the leading cause of death in Danon disease. We report a case of a 24-month-old boy with hemizygous LAMP2 mutation who presented with failure to thrive and early-onset hypertrophic cardiomyopathy. We applied targeted exome sequencing and found a novel hemizygous c.692del variant in exon 5 of the LAMP2 gene, resulting a frameshift mutation p.Thr231Ilefs*11. Our study indicates that target next-generation sequencing can be used as a fast and highly sensitive screening method for inherited cardiomyopathy.

• Clinical and Experimental Pediatrics
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• v.55 no.9
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• pp.350-353
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• 2012

An 18-year-old boy was admitted with chest discomfort, nausea, and dyspnea at rest. At the age of 3 years, he underwent muscle biopsy and dystrophin gene analysis owing to an enlarged calf muscle and elevated serum kinase level (6,378 U/L) without overt weakness; based on the results, Becker muscular dystrophy (BMD) was diagnosed. The dystrophin gene showed deletion of exons 45 to 49. He remained ambulant and could step upstairs without significant difficulties. A chest roentgenogram showed cardiomegaly (cardiothoracic ratio, 54%), and his electrocardiogram (ECG) showed abnormal ST-T wave, biatrial enlargement, and left ventricular hypertrophy. The 2-dimensional and M-mode ECGs showed a severely dilated left ventricular cavity with diffuse hypokinesis. The systolic indices were reduced, including fractional shortening (9%) and ejection fraction (19%). Despite receiving intensive medical treatment, he died from congestive heart failure 5 months after the initial cardiac symptoms. We report a case of BMD with early-onset dilated cardiomyopathy associated with deletion of exons 45 to 49. Early cardiomyopathy can occur in BMD patients with certain genotypes; therefore, careful follow-up is required even in patients with mild phenotypes of BMD.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.22 no.1
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• pp.1-8
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• 2022

Long-chain fatty acid oxidation disorders (LC-FAOD) are an autosomal recessive inherited rare disease group that result in an acute metabolic crisis and chronic energy deficiency owing to the deficiency in an enzyme that converts long-chain fatty acids into energy. LC-FAOD includes carnitine palmitoyltransferase type 1 (CPT1), carnitine-acylcarnitine translocase (CACT), carnitine palmitoyltransferase type 2 (CPT2), very long-chain acyl-CoA dehydrogenase (VLCAD), long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD), and trifunctional protein (TFP) deficiencies. Common symptoms of LC-FAOD are hypoketotic hypoglycemia, cardiomyopathy, and myopathy. Depending on symptom onset, the disease can be divided as neonatal period, late infancy and early childhood, adolescence, or adult onset, but symptoms can appear at any time. The neonatal screening test (NBS) can be used to identify the characteristic plasma acylcarnitine profiles for each disease and confirmed by deficient enzyme analysis or molecular testing. Before introduction of NBS, the mortality rate of LC-FAOD was very high. With NBS implementation as routine neonatal care, the mortality rate was dramatically decreased, but severe symptoms such as rhabdomyolysis recur frequently and affect the quality of life. Triheptanoin (Dojolvi^®), the first drug for pediatric and adult patients with molecularly confirmed LC-FAOD, has recently been approved by the US Food and Drug Administration in 2020. In this review, the diagnosis of LC-FAOD and treatment including triheptanoin are summarized.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.22 no.1
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• pp.21-27
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• 2022

Very long-chain acyl-coenzyme A dehydrogenase (VLCAD) deficiency (VLCADD) leads to a defective 𝛽-oxidation, specifically during prolonged fasting, infection, or exercise. Patients with VLCADD usually suffer from cardiomyopathy, hypoketotic hypoglycemia, hepatic dysfunction, exercise intolerance, muscle pain, and rhabdomyolysis, and sometimes succumb to sudden death. VLCADD is generally classified into three phenotypes: severe early-onset cardiac and multiorgan failure, hypoketotic hypoglycemia, and later-onset episodic myopathy. Diagnostic evaluation comprises acylcarnitine analysis, genetic analysis, and VLCAD activity assay. In the acylcarnitine analysis, the key metabolites are C14:1, C14:2, C14, and C12:1. A C14:1 level >1 mmol/L strongly suggests VLCADD. Various treatment recommendations are available for this condition. Dietary management includes decreasing fat content, increasing medium-chain triglyceride levels, and decreasing fasting periods. Supplementation with L-carnitine is controversial. Triheptanoin (a seven-carbon fatty acid triglyceride) treatment demonstrates improvement of cardiac functions. Bezafibrate may improve the quality of life of patients with VLCAD.

• Clinical and Experimental Pediatrics
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• v.62 no.6
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• pp.224-234
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• 2019

Purpose: Pompe disease (PD) is an autosomal recessive disorder caused by a deficiency of acid alpha-glucosidase resulting from pathogenic GAA variants. This study describes the clinical features, genotypes, changes before and after enzyme replacement therapy (ERT), and long-term outcomes in patients with infantile-onset PD (IOPD) and late-onset PD (LOPD) at a tertiary medical center. Methods: The medical records of 5 Korean patients (2 male, 3 female patients) diagnosed with PD between 2002 and 2013 at Samsung Medical Center in Seoul, Republic of Korea were retrospectively reviewed for data, including clinical and genetic characteristics at diagnosis and clinical course after ERT. Results: Common initial symptoms included hypotonia, cyanosis, and tachycardia in patients with IOPD and limb girdle weakness in patients with LOPD. Electrocardiography at diagnosis revealed hypertrophic cardiomyopathy in all patients with IOPD who showed a stable disease course during a median follow-up period of 10 years. Patients with LOPD showed improved hepatomegaly and liver transaminase level after ERT. Conclusion: As ERT is effective for treatment of PD, early identification of this disease is very important. Thus, patients with IOPD should be considered candidates for clinical trials of new drugs in the future.

• Annals of Pediatric Endocrinology and Metabolism
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• v.23 no.4
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• pp.176-181
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• 2018

Noonan syndrome (NS) is an autosomal dominant disorder that involves multiple organ systems, with short stature as the most common presentation (>70%). Possible mechanisms of short stature in NS include growth hormone (GH) deficiency, neurosecretory dysfunction, and GH resistance. Accordingly, GH therapy has been carried out for NS patients over the last three decades, and multiple studies have reported acceleration of growth velocity (GV) and increase of height standard deviation score (SDS) in both prepubertal and pubertal NS patients upon GH therapy. One year of GH therapy resulted in almost doubling of GV compared with baseline; afterwards, the increase in GV gradually decreased in the following years, showing that the effect of GH therapy wanes over time. After four years of GH therapy, ~70% of NS patients reached normal height considering their age and sex. Early initiation, long duration of GH therapy, and higher height SDS at the onset of puberty were associated with improved final height, whereas gender, dosage of GH, and the clinical severity did not show significant association with final height. Studies have reported no significant adverse events of GH therapy regarding progression of hypertrophic cardiomyopathy, alteration of metabolism, and tumor development. Therefore, GH therapy is effective for improving height and GV of NS patients; nevertheless, concerns on possible malignancy remains, which necessitates continuous monitoring of NS patients receiving GH therapy.

• Clinical and Experimental Pediatrics
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• v.50 no.2
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• pp.213-217
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• 2007

Pompe disease is a genetic disorder caused by a deficiency of acid ${\alpha}$-glucosidase (GAA). Infantile onset Pompe disease is uniformly lethal. Affected infants generally present in the first few months of life with hypotonia, generalized muscle weakness, and a hypertrophic cardiomyopathy, which is rapidly followed by death, usually by the age of one. The late-onset form is characterized less severe symptoms and prognosis. Therapy for Pompe disease is intended to directly address the underlying metabolic defect via intravenous infusions of recombinant human GAA to replace the missing enzyme. We report a case of atypical infantile-onset Pompe disease that presented symptoms in infancy but had less severe clinical manifestations and improved after GAA enzyme replacement ($Myozyme^{(R)}$, Genzyme Co., MA, USA) therapy. It is very important that pediatricians become aware of signs and symptoms of Pompe disease, such as a nasal voice or a waddling gait at an early stage so that these patients can benefit from appropriate GAA replacement therapy as soon as possible.