• Journal of Genetic Medicine
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• v.18 no.1
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• pp.70-74
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• 2021

Cohen-Gibson syndrome (CGS) was first reported by Cohen et al., who identified the mutation of the gene encoding the embryonic ectoderm development (EED) in a patient with phenotypes similar to Weaver syndrome. CGS manifests as an overgrowth and intellectual disability, in addition to the characteristic facial features and organ anomalies. CGS has been reported in only 11 unrelated patients since 2015. A girl aged 6 years and 3 months presented with seizures. She had macrosomia, a dysmorphic face, and intellectual disability. Her mother and younger sister and brother also had macrosomia, intellectual disability, and similar facial features; additionally, her mother experienced seizures and had an arachnoid cyst, while her siblings had valvar pulmonary stenosis. Whole-exome sequencing for the proband revealed a mutation of EED (c.581A>G, p.Asn194Ser), which was also verified in the mother and both siblings using Sanger sequencing. This is the first report of familial CGS.

• Journal of Genetic Medicine
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• v.19 no.2
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• pp.100-104
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• 2022

The gene encoding solute carrier family 9 member 6 (SLC9A6) on Xq26.3 is associated with Christianson syndrome (CS) mimicking Angelman syndrome. In CS, developmental and epileptic encephalopathy (DEE) appears in about 20%, and DEE with spike-and-wave activation in sleep (SWAS) is reported only in several cases. A 10-year-old boy with DEE showed multidrug resistant focal seizures from 6 months of age. He had progressive microcephaly, regression, global developmental delay without speech, hyperkinesia, and truncal ataxia; he had a long thin face, esotropia, and happy demeanor. Brain magnetic resonance imaging demonstrated cerebellar atrophy. Electroencephalogram at 7.5 years of age showed nearly continuous diffuse paroxysms in slow wave sleep. The seizures were responsive to corticosteroids for a while. Trio whole exome sequencing exhibited a likely pathogenic variant of SLC9A6 in the proband and his asymptomatic mother: c.1194dup (p.Leu399AlafsTer12). This is a rare case report of CS with DEE-SWAS in a Korean patient.

• Journal of Genetic Medicine
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• v.16 no.1
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• pp.15-18
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• 2019

SHORT syndrome is an extremely rare congenital condition due to a chromosomal mutation of the PIK3R1 gene found at 5q13.1. SHORT is a mnemonic representing six manifestations of the syndrome: (S) short stature, (H) hyperextensibility of joints and/or inguinal hernia, (O) ocular depression, (R) Rieger anomaly, and (T) teething delay. Other key aspects of this syndrome not found in the mnemonic include lipodystrophy, triangular face with dimpled chin (progeroid facies, commonly referred to as facial gestalt), hearing loss, vision loss, insulin resistance, and intrauterine growth restriction (IUGR). 3q duplication syndrome is rare syndrome that occurs due to a gain of function mutation found at 3q25.31-33 that presents with a wide array of manifestations including internal organ defects, genitourinary malformations, hand and foot deformities, and mental disability. We present a case of a 2 year and 3 month old male with SHORT syndrome and concurrent 3q duplication syndrome. The patient presented at birth with many of the common manifestations of SHORT syndrome such as bossing of frontal bone of skull, triangular shaped face, lipodystrophy, micrognathia, sunken eyes, and thin, wrinkled skin (progeroid appearance). Additionally, he presented with findings associated with 3q duplication syndrome such as cleft palate and cryptorchidism. Although there is no specific treatment for these conditions, pediatricians should focus on referring patients to various specialists in order to treat each individual manifestation.

• Journal of Genetic Medicine
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• v.14 no.1
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• pp.23-26
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• 2017

Isolated 3-methylcrotonyl-CoA carboxylase deficiency is an autosomal recessive disorder affecting leucine metabolism; it is one of the most common inborn metabolic diseases detected in newborn screening. Mutations in the genes MCCC1 or MCCC2 cause a defect in the enzyme 3-methylcrotonyl-CoA carboxylase, with MCCC2 mutations being the form predominantly reported in Korea. The majority of infants identified by neonatal screening usually appear to be asymptomatic and remain healthy; however, some patients have been reported to exhibit mild to severe metabolic decompensation and neurologic manifestations. Here we report the clinical features of a patient with asymptomatic 3-methylcrotonyl-CoA carboxylase deficiency and novel heterozygous MCCC1 mutations.

• Journal of Genetic Medicine
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• v.13 no.1
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• pp.46-50
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• 2016

Achondroplasia and hypochondroplasia are the two most common forms of short-limb dwarfism. They are autosomal dominant diseases that are characterized by a rhizomelic shortening of the limbs, large head with frontal bossing, hypoplasia of the mid-face, genu varum and trident hands. Mutations in the fibroblast growth factor receptor-3 (FGFR3) gene, which is located on chromosome 4p16.3, have been reported to cause achondroplasia and hypochondroplasia. More than 98% of achondroplasia cases are caused by the G380R mutation (c.1138G>A or c.1138G>C). In contrast, the N540K mutation (c.1620C>A) is detected in 60-65% of hypochondroplasia cases. Tests for common mutations are often unable to detect the mutation in patients with a clinical diagnosis of hypochondroplasia. In this study, we presented a case of familial hypochondroplasia with a rare mutation in FGFR3 identified by next generation sequencing.

• Journal of Genetic Medicine
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• v.10 no.1
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• pp.1-6
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• 2013

Chronic granulomatous disease (CGD) is a rare inherited disorder of a defective NADPH oxidase enzyme, resulting in very low or no production of superoxide and subsequent reactive oxygen species. Consequently, patients with CGD are highly susceptible to severe bacterial and fungal infections. CGD is a genetically heterogeneous disease caused by defects in any one of the genes encoding the NADPH oxidase components. CGD generally affects about 3-4 per 1,000,000 individuals; thus, it is surprising that the prevalence of CGD on Jeju Island is 34.3 per 1,000,000 individuals. At present, 20 patients with CGD from 14 unrelated families on Jeju Island have been identified; nine males and 11 females. All patients with CGD tested on Jeju Island had an identical and homozygous mutation (c.7C>T in CYBA, p.Q3X in $p22^{phox}$). Therefore, all patients were autosomal recessive form of CGD. This strongly suggests that the unique and identical mutation in CYBA may be inherited from a common proband. Using mutation-specific primers to detect the mutated allele in CYBA, the frequency of subjects carrying a mutated allele was 1.3% of enrolled subjects from Seogwipo City. Further studies are necessary to elucidate how frequently this mutant allele occurs in the population on Jeju Island. Additionally, it is important to construct a national registry system to understand the pathophysiology of CGD and develop a strategy for long-term therapy.

• Journal of Genetic Medicine
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• v.10 no.2
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• pp.81-87
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• 2013

Pseudohypoaldosteronism (PHA), a rare syndrome of systemic or renal mineralocorticoid resistance, is clinically characterized by hyperkalemia, metabolic acidosis, and elevated plasma aldosterone levels with either renal salt wasting or hypertension. PHA is a heterogeneous disorder both clinically and genetically and can be divided into three subgroups; PHA type 1 (PHA1), type 2 (PHA2) and type 3 (PHA3). PHA1 and PHA2 are genetic disorders, and PHA3 is a secondary disease of transient mineralocorticoid resistance mostly associated with urinary tract infections and obstructive uropathies. PHA1 includes two different forms with different severity of the disease and phenotype: a systemic type of disease with autosomal recessive inheritance (caused by mutations of the amiloride-sensitive epithelial sodium channel, ENaC) and a renal form with autosomal dominant inheritance (caused by mutations of the mineralocorticoid receptor, MR). In the kidneys, the distal nephron takes charge of the fine regulation of water absorption and ion handling under the control of aldosterone. Two major intracellular actors necessary for the action of aldosterone are the MR and the ENaC. Impairment of the intracellular aldosterone signal transduction pathway results in resistance to the action of mineralocorticoids, which leads to PHA. Herein, ion handling the distal nephron and the clinico-genetic findings of PHA are reviewed with special emphasis on PHA type 1.

• Journal of Genetic Medicine
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• v.18 no.1
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• pp.31-37
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• 2021

Purpose: To summarize the results of chromosomal microarray analysis (CMA) for copy number variants (CNVs) detection and clinical utility in a single tertiary hospital. Materials and Methods: We performed CMA in 46 patients over the course of two years. Detected CNVs were classified into five categories according to the American College of Medical Genetics and Genomics guidelines and correlated with clinical manifestations. Results: A total of 31 CNVs were detected in 19 patients, with a median CNV number per patient of two CNVs. Among these, 16 CNVs were classified as pathogenic (n=3) or likely pathogenic (LP) (n=11) or variant of uncertain significance (n=4). The 16p11.2 deletion and 16p13.11 deletion classified as LP were most often detected in 6.5% (3/46), retrospectively. CMA diagnostic yield was 24.3% (9/37 patients) for symptomatic patients. The CNVs results of the commercial newborn screening test using next generation sequencing platforms showed high concordance with CMA results. Conclusion: CMA seems useful as a first-tier test for developmental delay with or without congenital anomalies. However, the classification and interpretation of CMA still remained a challenge. Further research is needed for evidence-based interpretation.

• Journal of Genetic Medicine
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• v.15 no.1
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• pp.38-42
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• 2018

WAGR (Wilms tumor, aniridia, genitourinary anomalies, and mental retardation) syndrome is a rare contiguous gene deletion syndrome caused by deleting genes including WT1 and PAX6 genes in 11p13 region, which is characterized by Wilms tumor, aniridia, genitourinary abnormalities, and intellectual disability. We report the clinical and cytogenetic characteristics of one Korean patient with WAGR syndrome. The patient shows bilateral sporadic aniridia and genital anomalies at 2 months of age. A heterozygous 14.5 Mb interstitial deletion of 11p14.3p12 region was detected by array comparative genomic hybridization. At 2 years and 10 months of age, Wilms tumor is found through regularly abdominal ultrasonography and treated by chemotherapy, radiation therapy and surgery.

• Journal of Genetic Medicine
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• v.16 no.1
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• pp.1-9
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• 2019

Noonan syndrome (NS) and NS-related disorders (cardio-facio-cutaneous syndrome, Costello syndrome, NS with multiple lentigines, or LEOPARD [lentigines, ECG conduction abnormalities, ocular hypertelorism, pulmonic stenosis, abnormal genitalia, retardation of growth and sensory neural deafness] syndrome) are collectively named as RASopathies. Clinical presentations are similar, featured with typical facial features, short stature, intellectual disability, ectodermal abnormalities, congenital heart diseases, chest & skeletal deformity and delayed puberty. During past decades, molecular etiologies of RASopathies have been growingly discovered. The functional perturbations of the RAS-mitogen-activated protein kinase pathway are resulted from the mutation of more than 20 genes (PTPN11, SOS1, RAF1, SHOC2, BRAF, KRAS, NRAS, HRAS, MEK1, MEK2, CBL, SOS2, RIT, RRAS, RASA2, SPRY1, LZTR1, MAP3K8, MYST4, A2ML1, RRAS2). The PTPN11 (40-50%), SOS1 (10-20%), RAF1 (3-17%), and RIT1 (5-9%) mutations are common in NS patients. In this review, the constellation of overlapping clinical features of RASopathies will be described based on genotype as well as their differential diagnostic points and management.