• Childhood Kidney Diseases
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• v.27 no.2
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• pp.70-75
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• 2023

Dent disease is a rare inherited kidney tubulopathy caused by mutations in either the CLCN5 (Dent disease 1) or OCRL1 (Dent disease 2) genes, and which is often underdiagnosed in practice. A diagnosis is clinically suspected in patients with low-molecular-weight proteinuria, hypercalciuria, and one of the following: hematuria, nephrolithiasis, nephrocalcinosis, hypophosphatemia, or chronic kidney disease. Inheritance is X-linked recessive, meaning, these symptoms are generally only found in males; female carriers may have mild phenotypes. Genetic testing is only a method to confirm the diagnosis, approximately 25% to 35% of patients have neither the CLCN5 nor OCRL1 pathogenic variants (Dent disease 3), making diagnosis more challenging. The genotype-phenotype correlations are not evident with the limited clinical data available. As with many other genetic diseases, the management of patients with Dent disease concentrates on symptom relief rather than any causative process. The current treatments are mainly supportive to reduce hypercalciuria and prevent nephrolithiasis. Chronic kidney disease progresses to end-stage between the ages of the third to fifth decades in 30% to 80% of affected males. In this review, we aimed to summarize the literature on Dent disease and reveal the clinical characteristics and molecular basis of Korean patients with Dent disease.

• The Korean Journal of Physiology and Pharmacology
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• v.21 no.4
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• pp.439-447
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• 2017

Myotonia congenita (MC) is a genetic disease that displays impaired relaxation of skeletal muscle and muscle hypertrophy. This disease is mainly caused by mutations of CLCN1 that encodes human skeletal muscle chloride channel (CLC-1). CLC-1 is a voltage gated chloride channel that activates upon depolarizing potentials and play a major role in stabilization of resting membrane potentials in skeletal muscle. In this study, we report 4 unrelated Korean patients diagnosed with myotonia congenita and their clinical features. Sequence analysis of all coding regions of the patients was performed and mutation, R47W and A298T, was commonly identified. The patients commonly displayed transient muscle weakness and only one patient was diagnosed with autosomal dominant type of myotonia congenita. To investigate the pathological role of the mutation, electrophysiological analysis was also performed in HEK 293 cells transiently expressing homo-or heterodimeric mutant channels. The mutant channels displayed reduced chloride current density and altered channel gating. However, the effect of A298T on channel gating was reduced with the presence of R47W in the same allele. This analysis suggests that impaired CLC-1 channel function can cause myotonia congenita and that R47W has a protective effect on A298T in relation to channel gating. Our results provide clinical features of Korean myotonia congenita patients who have the heterozygous mutation and reveal underlying pathophyological consequences of the mutants by taking electrophysiological approach.

• The Korean Journal of Physiology and Pharmacology
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• v.27 no.1
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• pp.85-94
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• 2023

Ion channels regulate a large number of cellular functions and their functional role in many diseases makes them potential therapeutic targets. Given their diverse distribution across multiple organs, the roles of ion channels, particularly in age-associated transcriptomic changes in specific organs, are yet to be fully revealed. Using RNA-seq data, we investigated the rat transcriptomic profiles of ion channel genes across 11 organs/tissues and 4 developmental stages in both sexes of Fischer 344 rats and identify tissue-specific and age-dependent changes in ion channel gene expression. Organ-enriched ion channel genes were identified. In particular, the brain showed higher tissue-specificity of ion channel genes, including Gabrd, Gabra6, Gabrg2, Grin2a, and Grin2b. Notably, age-dependent changes in ion channel gene expression were prominently observed in the thymus, including in Aqp1, Clcn4, Hvcn1, Itpr1, Kcng2, Kcnj11, Kcnn3, and Trpm2. Our comprehensive study of ion channel gene expression will serve as a primary resource for biological studies of aging-related diseases caused by abnormal ion channel functions.

• Molecular & Cellular Toxicology
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• v.3 no.1
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• pp.60-67
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• 2007

Gentamicin is a broad-spectrum aminoglycoside antibiotic used in the treatment of bacterial infection. Although side effects of gentamicin such as nephrotoxicity and ototoxicity have been investigated, the information on the hepatic effects of gentamicin is still limited. In the present study, gene expression profiles were analyzed in the liver of gentamicin treated mice using Affymetrix GeneChip$^{(R)}$ Mouse Expression 430A 2.0 Array. Totally, 400 genes were identified as being either up- or down-regulated over 1.5-fold changes (P<0.01) in the liver of gentamicin treated mice. Among these deregulated genes, 16 up-regulated genes mainly involved in transport (Kif5b, Pex14, Rab14, Clcn3, and Necap1) and 20 down-regulated genes involved in lipid and other metabolisms (Hdlbp, Gm2a, Uroc1, and Dak) were selected using k-means clustering algorithm. The functional classification of differentially expressed genes represented that several stress-related genes were regulated in the liver by gentamicin treatment. This data may contribute in understanding the molecular mechanism in the liver of gentamicin treated mice.

• Childhood Kidney Diseases
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• v.7 no.2
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• pp.234-238
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• 2003

Fanconi syndrome is a generalized functional disorder of the proximal tubule of the kidney and is characterized by aminoaciduria, glycosuria, hyperphosphaturia, dehydration, rickets, and growth failure. Nephrocalcinosis and hypercalciuria are rare manifestations of Fanconi syndrome. There is no case report of Fanconi syndrome complicated with nephrocalcinosis and hypercalciuria in Korea. A 6-year-old boy presented with genu valgum and waddling gaits for about 3 years. There was no family history of renal disease and his physical examination was normal except for genu valgum and corrected cleft lip and palate. Laboratory investigations showed generalized aminoaciduria, glycosuria, hyperphosphaturia, hypercalciuria, and low-molecular weight proteinuria including ${\beta}$-microglobulin. Serum 25-OH vitamin $D_3$ was within the normal range, and $1,25-(OH)_2$ vitamin $D_3$ was elevated. Bilateral renal medullary hyperechogenicity was demonstrated by ultrasonography. Analysis of the CLCN5 gene revealed no mutation. Here we describe a boy with Fanconi syndrome complicated with nophrocalcinosis and discuss the differential diagnosis.

• Pediatric Infection and Vaccine
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• v.23 no.1
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• pp.72-76
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• 2016

Infantile osteopetrosis is a rare congenital disorder caused by abnormal bone resorption. Patients with osteopetrosis can have severe anemia, thrombocytopenia, hepatosplenomegaly, rickets, visual impairment, and deafness. Cytomegalovirus also can cause a congenital infection with anemia, thrombocytopenia, hepatosplenomegaly, and calcifications in the brain. We report a 38-day-old infant with severe hepatosplenomegaly, thrombocytopenia, hypocalcemia, and growth failure. Real time polymerase chain reaction detected cytomegalovirus in the plasma. Skeletal radiography revealed generalized bone sclerosis. He was diagnosed with osteopetrosis along with cytomegalovirus infection. Only the test for mutation of the CLCN7 gene, representing the most common and heterogeneous form of osteopetrosis, was available, and the result was negative. With supportive care and antiviral treatment, severe thrombocytopenia due to the cytomegalovirus infection almost normalized despite the possible immunosuppression caused by osteopetrosis. We present the first report of an infant who suffered from osteopetrosis and CMV infection which was successfully treated by long term antiviral agent therapy.