Leber congenital amaurosis (LCA) is the most severe form of inherited retinal dystrophy, and invariably leads to blindness. LCA is a genetically and clinically heterogenous disorder. Although more than nine genes have been found to be associated with LCA, they only account for about half of LCA cases. We performed a comprehensive mutational analysis on nine known genes in 20 unrelated patients to investigate the genetic cause of LCA in Koreans.
All exons and flanking regions of the nine genes (AIPL1, CRB1, CRX, GUCY2D, RDH12, RPE65, RPGRIP1, LRAT, and TULP1) were analyzed by direct sequencing. We also screened our patients for the common CEP290: c.2991+1655A>G mutation found in Caucasian.
Six different mutations including four novel ones were identified in three patients (15.0%): one frameshift, one nonsense, one splicing, and three missense mutations. These patients were compound heterozygotes and harbored two different mutations in CRB1, RPE65, and RPGRIP1, respectively. We identified three novel unclassified missense variants in RPGRIP1 of the three patients. These patients were heterozygous for each variant and did not have a large deletion or duplication in the same gene.
This comprehensive mutational analysis shows marked genetic heterogeneity in Korean LCA patients and reveals a mutation spectrum that differs from those previously reported. In turn, this suggests that a different strategy should be used for the molecular diagnosis of LCA in Koreans.
Brachydactyly type C (BDC) is characterized by shortening of the middle phalanges of the index, middle, and little fingers. Hyperphalangy of the index and middle finger and shortening of the first metacarpal can also be observed. BDC is a rare genetic condition associated with the GDF5 gene, and this condition has not been confirmed by genetic analysis so far in the Korean population. Herein, we present a case of a 6-yr-old girl diagnosed with BDC confirmed by molecular genetic analysis. The patient presented with shortening of the second and third digits of both hands. Sequence analysis of the GDF5 gene was performed and the pathogenic mutation, c.1312C>T (p.Arg438Cys), was identified. Interestingly, this mutation was previously described in a patient who presented with the absence of the middle phalanges in the second through fifth toes. However, our patient showed no involvement of the feet. Considering intrafamilial and interfamilial variability, molecular analysis of isolated brachydactyly is warranted to elucidate the genetic origin and establish a diagnosis.
Brachydactyly; GDF5 gene; Mutational analysis
Group B streptococcus (GBS) infection is a leading cause of neonatal morbidity and mortality worldwide. Here, we present the analytical and diagnostic usefulness of a new real-time PCR-based assay (Xpert GBS; Cepheid, USA) for rapid and accurate prenatal GBS screening.
We enrolled 175 pregnant women who were between 35 and 39 weeks of gestation. The analytical performance of the Xpert GBS assay was first tested using a reference GBS strain. Next, to test diagnostic performance, rectovaginal swabs were obtained from pregnant women who visited the hospital for regular antenatal screening after 34 weeks of gestation. The results of the Xpert GBS assay were compared to those of standard culture for the detection of prenatal GBS colonization.
When any positive result from Xpert GBS or culture was considered a true positive, the sensitivity of the Xpert GBS assay and culture were 91% (20/22; 95% CI [confidence interval], 72-98) and 68% (15/22; 95% CI, 47-84), respectively. The specificity of both methods was 100% (153/153; 95% CI, 97-100). The sensitivity and specificity of the Xpert GBS assay, using the culture results as a reference, were 86.7% and 95.6%, respectively. In the Xpert GBS assay, the median threshold cycle of vaginally colonized samples was significantly lower than rectally colonized samples (P<0.01).
The Xpert GBS assay is an accurate, rapid, easy-to-use test for the detection of maternal GBS colonization in prenatal screening that might be especially useful in clinical settings where standard culture is not feasible.
Streptococcus agalactiae; Prenatal diagnosis; Real-time PCR
Genetic abnormalities in adult AML are caused most frequently by somatic mutations in exon 12 of the NPM1 gene, which is observed in approximately 35% of AML patients and up to 60% of patients with cytogenetically normal AML (CN-AML).
We performed mutational analysis, including fragment analysis and direct sequencing of exon 12 of the NPM1 gene, on 83 AML patients to characterize the NPM1 mutations completely.
In this study, NPM1 mutations were identified in 19 (22.9%) of the 83 AML patients and in 12 (42.9%) of the 28 CN-AML patients. Among the 19 patients with NPM1 mutations, type A NPM1 mutations were identified in 16 (84.2%) patients, whereas non-A type NPM1 mutations were observed in 3 (15.8%) patients. Two of the 3 non-A type NPM1 mutations were novel: c.867_868insAAAC and c.869_873indelCTTTAGCCC. These 2 novel mutant proteins display a nuclear export signal motif (L-xxx-L-xx-V-x-L) less frequently and exhibit a mutation at tryptophan 290 that disrupts the nucleolar localization signal.
This study suggests that novel NPM1 mutations may be non-rare and that supplementary sequence analysis is needed along with conventional targeted mutational analysis to detect non-A types of NPM1 mutations.
NPM1; Nucleophosmin; AML
This study was performed to characterize respiratory viral infections in pediatric patients undergoing hematopoietic stem cell transplantation (HSCT). Study samples included 402 respiratory specimens obtained from 358 clinical episodes that occurred in the 116 children of the 175 consecutive HSCT cohort at Seoul National University Children's Hospital, Korea from 2007 to 2010. Multiplex reverse-transcription polymerase chain reactions were performed for rhinovirus, respiratory syncytial virus (RSV), parainfluenza viruses (PIVs), adenovirus, human coronavirus (hCoV), influenza viruses and human metapneumovirus. Viruses were identified in 89 clinical episodes that occurred in 58 patients. Among the 89 clinical episodes, frequently detected viruses were rhinovirus in 25 (28.1%), RSV in 23 (25.8%), PIV-3 in 16 (18.0%), adenovirus in 12 (13.5%), and hCoV in 10 (11.2%). Lower respiratory tract infections were diagnosed in 34 (38.2%). Neutropenia was present in 24 (27.0%) episodes and lymphopenia was in 31 (34.8%) episodes. Sixty-three percent of the clinical episodes were hospital-acquired. Three patients died of respiratory failure caused by respiratory viral infections. Respiratory viral infections in pediatric patients who have undergone HSCT are common and are frequently acquired during hospitalization. Continuous monitoring is required to determine the role of respiratory viruses in immunocompromised children and the importance of preventive strategies.
Hematopoietic Stem Cell Transplantation; Respiratory Virus; Respiratory Infections
Fanconi anemia (FA) is a rare genetic disorder affecting multiple body systems. Genetic testing, including prenatal testing, is a prerequisite for the diagnosis of many clinical conditions. However, genetic testing is complicated for FA because there are often many genes that are associated with its development, and large deletions, duplications, or sequence variations are frequently found in some of these genes. This study describes successful genetic testing for molecular diagnosis, and subsequent prenatal diagnosis, of FA in a patient and his family in Korea. We analyzed all exons and flanking regions of the FANCA, FANCC, and FANCG genes for mutation identification and subsequent prenatal diagnosis. Multiplex ligation-dependent probe amplification analysis was performed to detect large deletions or duplications in the FANCA gene. Molecular analysis revealed two mutations in the FANCA gene: a frameshift mutation c.2546delC and a novel splice-site mutation c.3627-1G>A. The FANCA mutations were separately inherited from each parent, c.2546delC was derived from the father, whereas c.3627-1G>A originated from the mother. The amniotic fluid cells were c.3627-1G>A heterozygotes, suggesting that the fetus was unaffected. This is the first report of genetic testing that was successfully applied to molecular diagnosis of a patient and subsequent prenatal diagnosis of FA in a family in Korea.
Fanconi anemia; FANCA; Molecular diagnosis; Prenatal diagnosis
Lysinuric protein intolerance (LPI) is a rare inherited metabolic disease, caused by defective transport of dibasic amino acids. Failure to thrive, hepatosplenomegaly, hematological abnormalities, and hyperammonemic crisis are major clinical features. However, there has been no reported Korean patient with LPI as of yet. We recently encountered a 3.7-yr-old Korean girl with LPI and the diagnosis was confirmed by amino acid analyses and the SLC7A7 gene analysis. Her initial chief complaint was short stature below the 3rd percentile and increased somnolence for several months. Hepatosplenomegaly was noted, as were anemia, leukopenia, elevated levels of ferritin and lactate dehydrogenase, and hyperammonemia. Lysine, arginine, and ornithine levels were low in plasma and high in urine. The patient was a homozygote with a splicing site mutation of IVS4+1G > A in the SLC7A7. With the implementation of a low protein diet, sodium benzoate, citrulline and L-carnitine supplementation, anemia, hyperferritinemia, and hyperammonemia were improved, and normal growth velocity was observed.
Lysinuric Protein Intolerance; Amino Acids, Basic; Hyperammonemia; SLC7A7
Loeys-Dietz syndrome is a recently described autosomal dominant disorder caused by mutations in the genes for transforming growth factor-beta receptor type 1 or 2 (TGF-ßR 1/2). The syndrome predisposes patients to aortic aneurysm and dissections, along with craniofacial and musculoskeletal abnormalities. Here we report the case of an adolescent who underwent serial near total aortic replacement, from the aortic valve to the descending aorta. Loeys-Dietz syndrome was confirmed in this case by the detection of a mutation in the TGF-ßR 2 gene.
Loeys-Dietz syndrome; Aortic aneurysm; Craniofacial abnormalities; Transforming growth factor-beta type II receptor
Multiple-locus variable-number tandem-repeat fingerprinting (MLVF) is based on multiplex PCR, utilizing variable number tandem repeat. Our goal was to compare the performance of MLVF in distinguishing clinical Staphylococcus aureus isolates with that of pulsed-field gel electrophoresis (PFGE), which has traditionally been the gold standard.
Sixty-three clinically significant S. aureus isolates were tested using both PFGE and MLVF. Multiplex PCR for MLVF was performed using PCR primers for clfA, clfB, sdrCDE, sspA, and spa. PFGE was performed with genomic DNA fragments generated by SmaI endonuclease digestion. Banding patterns of MLVF or PFGE were analyzed using InfoQuestFP software.
The hands-on time of our modified method was about 3 h, on average, for each of 18 isolates. PFGE (80% cutoff) or MLVF (75% cutoff) separated all of the 63 isolates into 13 and 12 types, respectively. Three types generated by PFGE were identical to those generated by MLVF. PFGE and MLVF yielded similar Simpson's diversity indices, indicating similar discriminatory power. The overall concordance between PFGE and MLVF was low, as represented by adjusted Rand indices (0.266-0.278). PFGE predicted MLVF type better than MLVF predicted PFGE type, as reflected by Wallace coefficients (PFGE cutoff 80% vs. MLVF cutoff 75%, 0.389 vs. 0.233). Analysis of the relationship between a pair of isolates showed 91.0% concordance between the PFGE (80% cutoff) and MLVF (75% cutoff).
Our simple, low-cost, modified MLVF protocol can effectively discriminate between S. aureus clinical isolates. MLVF can replace PFGE for the hospital infection control of S. aureus.
Staphylococcus aureus; Pulsed-field gel electrophoresis; Multiple-locus variable-number tandem-repeat fingerprinting
Hereditary hemolytic anemia comprises a group of disorders in which red blood cells are destroyed faster than they are produced in the bone marrow; various hereditary factors can cause this condition, including production of defective Hb and erythrocyte membrane. Recently, we identified Hb Koriyama, a rare Hb variant that was undetectable in Hb electrophoresis and stability tests, in a patient with severe hemolytic anemia. This is the first study to show the nucleotide-level sequence variations in Hb Koriyama. On the basis of our results, we conclude that unstable Hb may not be detectable by conventional Hb electrophoresis or stability tests. Thus, we suggest further genetic workup in cases of unexplained hereditary hemolytic anemia.
Hemoglobinopathy; Hemoglobin variant; Hb Koriyama
Loss of heterozygosity (LOH) in chromosome 6p has been reported in a number of tumors and some hematologic malignancies, including ALL. LOH in chromosome 6p, on which the HLA genes are located, can give rise to false homozygosity results in HLA genotyping of patients with hematologic malignancies. Here we report false homozygosity results in HLA genotyping due to the loss of whole chromosome 6 in the neoplastic cells of a patient with ALL. A 33-yr-old Korean female patient was admitted for the evaluation of leukocytosis detected during a workup for headache. Her initial white blood cell count was 336.9×109/L with 84% of blasts in the differential count. Precursor-B lymphoblastic leukemia was diagnosed from a subsequent bone marrow study. HLA high-resolution genotyping of the patient was requested at the time of diagnosis for possible hematopoietic stem cell transplantation. Homozygosity results (A*02:01, B*54:01, C*08:01, DQB1*04:01) were obtained, except for the DRB1 locus (DRB1*04:05, DRB1*11:01), in sequence-based typing. Conventional karyotyping of bone marrow metaphase cells revealed chromosomal abnormalities, with loss of multiple chromosomes including chromosome 6, and reduplication of the remaining chromosomes: 29,X,+X,+8,inv(9)(p11q13),+10,+14,+18,+21/58,idemX2/46,XX,inv(9). LOH at the HLA region was suspected and HLA genotyping was repeated with the peripheral blood in remission state after induction chemotherapy. All 5 HLA loci were typed as heterozygous (A*02:01, A*02:06, B*40:01, B*54:01, C*03:04, C*08:01, DRB1*04:05, DRB1*11:01, DQB1*03:01, DQB1*04:01). To avoid false HLA typing results in patients with hematologic malignancies, clinicians, as well as laboratory personnel, need to be aware of such problems and take appropriate precautions.
Loss of heterozygosity; HLA genotyping; Precursor-B lymphoblastic leukemia
QT prolongation is a serious adverse drug effect, which is associated with an increased risk of Torsade de pointes and sudden death. Many drugs, including both cardiac and non-cardiac drugs, have been reported to cause prolongation of QT interval. Although meperidine has not been considered proarrhythmic, we present a unique case of a 16-year-old boy without an underlying cardiac disease, who developed polymorphic ventricular tachycardia, ventricular fibrillation and QT prolongation after an intravenous meperidine injection. He had no mutation in long QT syndrome genes (KCNQ1, KCNH2, and SCN5A), but single nucleotide polymorphisms were reported, including H558R in SCNA5A and K897T in KCNH2.
Long QT syndrome; Meperidine; Torsade de pointes
Propionibacterium acnes is a gram-positive anaerobic bacillus and a normal inhabitant of the skin. Although it is often considered a contaminant of blood cultures, it can occasionally cause serious infections, including postoperative central nervous system infections. Here, we report the case of a 70-yr-old man who developed a large cerebral abscess caused by P. acnes 13 months after neurosurgery. Immediate gram staining of the pus from his brain revealed the presence of gram-positive coccobacilli. However, colony growth was observed only after 5 days of culture. Therefore, we performed 16S rRNA gene sequencing of the pus specimen. The isolate was identified as P. acnes. The colonies developed 9 days after the initial culture. The API Rapid ID 32A test (bioMérieux, France) was performed using a colony, but an unacceptable profile was obtained. Then, the pus was transferred into the enrichment broths of the BACTEC FX (Becton Dickinson, USA) and BacT/Alert 3D (bioMérieux, Organon Teknika, USA) systems, but only the BACTEC FX system could detect growth after 5 days. We performed 16S rRNA gene sequencing and API Rapid 32A profiling with a colony recovered from Brucella agar, which was inoculated with the microbial growth in the enrichment broth from the BACTEC FX system. The organism was identified as P. acnes by both methods. This case suggests that 16S rRNA gene sequencing may be a useful alternative for identifying slowly growing P. acnes from specimens that do not show growth after 5 days of culture.
Propionibacterium acnes; Brain abscess; 16S rRNA gene sequencing
To report the incidence and new findings of abnormal brain imaging studies associated with patients initially diagnosed with Leber's congenital amaurosis (LCA) without definite systemic abnormalities and to determine the need for brain imaging studies in these patients.
A retrospective review of medical records was performed in 83 patients initially diagnosed as LCA and without definite systemic abnormalities before the age of 6 months in 2 tertiary referral centers. Brain magnetic resonance imaging was performed in 31 of 83 patients (37.3%).
Six of 31 patients (19%) had radiologically documented brain abnormalities. Two patients had cerebellar vermis hypoplasia, 1 patient showed an absence of septum pellucidum, 2 subjects showed mild external hydrocephalus, and 1 patient was found to have a small cerebellum.
Approximately one fifth of the LCA patients in whom brain imaging was performed were associated with brain abnormalities, including the absence of septum pellucidum, which has not been documented in the literature. Brain imaging is mandatory in patients primarily diagnosed with LCA, even without definite neurologic or systemic abnormalities.
Cerebellar vermis hypoplasia; Leber's congenital amaurosis; Magnetic resonance imaging; Septum pellucidum
The Jervell and Lange-Nielsen syndrome (JLNS) is an autosomal recessive syndrome characterized by congenital deafness and cardiac phenotype (QT prolongation, ventricular arrhythmias, and sudden death). JLNS has been shown to occur due to homozygous mutation in KCNQ1 or KCNE1. There have been a few clinical case reports on JLNS in Korea; however, these were not confirmed by a genetic study. We identified compound heterozygous mutations in KCNQ1 in a 5-yr-old child with JLNS, who visited the hospital due to recurrent syncope and seizures and had congenital sensorineural deafness. His electrocardiogram revealed a markedly prolonged corrected QT interval with T wave alternans. The sequence analysis of the proband revealed the presence of novel compound heterozygous deletion/splicing error mutations (c.828-830 delCTC, p.S277del/c.921G>A, p.V307V). Each mutation in KCNQ1 was identified on the maternal and paternal side. With β-blocker therapy the patient has remained symptom-free for three and a half years.
Congenital Long QT Syndrome; Deafness; Mutation
Context: Enlargement of the vestibular aqueduct (EVA) is a commonly detected inner ear anomaly related to hearing loss and often associated with mutations of SLC26A4 encoding pendrin, a transmembrane exchanger of Cl−, I−, and HCO3−. Here we describe the phenotypes of 27 Korean EVA subjects and their SLC26A4 genotypes determined by bidirectional nucleotide sequencing. Results: The detected variants include two novel missense substitutions (p.V138L and p.P542R). We characterized the ability of p.V138L and p.P542R pendrin products to traffic to the plasma membrane in COS-7 cells and to transport Cl−, I−, and HCO3− in Xenopus oocytes. The results indicate that p.P542R is a benign polymorphic variant, whereas p.V138L is a pathogenic mutation. Since this and other studies of East Asian EVA cohorts show that the majority of SLC26A4 mutations affect either or both of two amplicons (exons 7–8 and 19), we developed a hierarchical protocol that integrates direct sequencing with denaturing high-performance liquid chromatography analyses for detection of SLC26A4 mutations in these populations. We validated the cost efficiency of the integrated protocol by a simulated screen of published East Asian EVA cohorts with known SLC26A4 genotypes. Conclusions: Our study further defines the spectrum of SLC26A4 mutations among East Asians and demonstrates a rapid and efficient protocol for their detection.
Multiple epiphyseal dysplasia is caused by heterogenous genotypes involving more than six genes. Recessive mutations in the DTDST gene cause a phenotype of recessive multiple epiphyseal dysplasia (rMED). The authors report a 9-yr old Korean girl with the rMED phenotype having novel compound heterozygous mutations in the DTDST gene, which were inherited from both parents. This is the first Korean rMED case attributed to DTDST mutations, and expands the spectrum of diseases caused by DTDST mutations.
Osteochondrodysplasias; Diastrophic Dysplasia Sulfate Transporter
Glutaric aciduria type I (GA I) is an autosomal recessive disorder caused by a deficiency of glutaryl-CoA dehydrogenase. Although over 400 patients confirmed as GA I have been reported, reports from the Asian population had contributed to the minor proportion. We recently diagnosed two cases of GA I confirmed with mutational analysis. Here, we present their rather atypical clinical presentations with genetic characteristics for the first time in Korea. Profound developmental delay from birth, association of hearing loss, and neurological improvement after surgical intervention, were considered to be different clinical features from most reported cases. One patient was a compound heterozygote for p.Ser139Leu and p.Asp220Tyr, and the other for p.Ser139Leu and Glu160X. The mutations of the two alleles (p.Asp220Tyr and p.Glu160X) were novel and reports of p.Ser139Leu were rare both in Western and other Asian populations. These might suggest different genetic spectrum of Korean GA I patients.
Glutaric Aciduria Type I; Glutaryl-CoA Dehydrogenase; Mutation; Korea
Since the first descriptions of Brugada as a new clinical entity defined by sudden cardiac death in patients with typical electrocardiogram (ECG) patterns, Brugada syndrome (BS) has been increasingly diagnosed. This syndrome is known as a disease that is inherited via an autosomal dominant trait, and the SCN5A mutation has been found in 20-25% of BS patients. Because BS primarily manifests in adulthood, little information is available on BS during childhood. Although there have been several reports on adult BS in Korea, pediatric BS has not been reported. Herein, we report on childhood BS in two families. One infantile BS patient and his family had a novel SCN5A mutation (c.4035G>T, p.W1345C, heterozygote) in domain III of the sodium channel.
Brugada syndrome; Tachycardia, ventricular
Reciprocal translocations involving the immunoglobulin loci and the cellular oncogene MYC are hallmark mutations of the human postgerminal center B cell neoplasm, Burkitt’s lymphoma. They are occasionally found in other B cell lymphomas, as well. Translocations involving the heavy chain locus (IGH) place the MYC gene either in cis with both the intronic enhancer Eµ and the IGH 3′ regulatory region (3′RR) or in cis with only the 3′RR. The result is deregulated MYC expression. Recent studies have led to some controversy as to when, during B lymphocyte development, IGH/MYC chromosome translocations take place. A related issue, relevant not only to lymphoma development but also to normal controls on IGH gene expression, is the stage, during B lymphocyte development, at which the 3′RR is capable of activating MYC expression. We have developed mice transgenic for a human MYC (hMYC) gene under control of the four core enhancers from the mouse Igh 3′RR. Unlike other transgenic mouse models where premature and inappropriate MYC expression disrupts normal B cell development, the hMYC transgene in these studies carries a mutation that prohibits MYC protein synthesis. As a result, hMYC expression can be analyzed in all of the normal B cell compartments. Our data show that hMYC is expressed almost exclusively in B-lineage cells and is induced to high levels as soon as bone marrow cells reach the immature B cell stage.
The authors report two cases of X-linked juvenile retinoschisis (XLRS) manifested as bilateral vitreous hemorrhage as early as in an 1-month-old infant and in a 3-month-old infant. The one-month-old male infant showed massive bilateral vitreous hemorrhage. During vitrectomy, thin membrane representing an inner part of schisis cavity was excised and intraschisis hemorrhage was evacuated. As intraschisis cavities were cleared, the stump of inner layer appeared as the demarcation line between the outer layer of the schisis retina and non-schisis retina. The other three-month-old male infant presenting with esodeviation also showed bilateral vitreous hemorrhage. Typical bilateral retinoschisis involving maculae could be seen through vitreous hemorrhage in both eyes on fundus examination. Spontaneous absorption of hemorrhage was observed on regular follow-up. XLRS could be manifested as massive hemorrhage inside or outside of the schisis cavity early in infancy.
Infant; Vitreous hemorrhage; X-linked juvenile retinoschisis
Background and Purpose
The LRRK2 (PARK8; OMIM607060) substitution was recently identified as a causative mutation for Parkinson's disease (PD). The pathologic heterogeneity of LRRK2-positive patients suggests that mutation of the LRRK2 gene is associated with the pathogenesis of PD and Parkinson-plus disorders, such as multiple system atrophy (MSA). We previously reported that the G2019S LRRK2 mutation-which is the most common LRRK2 mutation-was not found in a sample of 453 Korean PD patients. In the present study, we extended the screening for the G2019S mutation to a larger group of PD and MSA patients.
We performed a genetic analysis of the G2019S mutation in 877 patients with PD and 199 patients with MSA using a standard PCR and restriction digestion method.
None of the subjects carried the G2019S mutation.
The results of the present study support that the G2019S mutation is extremely rare in PD and is unlikely to be associated with MSA in the Korean population.
Parkinson's disease; multiple system atrophy; LRRK2; G2019S mutation
X-linked retinoschisis (XLRS) is a recessively inherited disorder that causes macular degeneration and resultant visual defect in young males. Many genetic studies had focused on the patients in Western countries. We characterized the mutational spectrum of the RS1 gene in Korean patients with XLRS, and aimed to provide genetic information of XLRS in an Asian population.
This study enrolled 17 unrelated probands and their mothers for molecular genetic evaluation. All exons and the flanking intronic regions of RS1 were analyzed by direct sequencing. We performed gene dosage analysis by semiquantitative multiplex PCR to rule out the possibility of duplication in a patient without a sequence variation. We also tried RT–PCR analysis in a case with a putative splicing mutation.
Genetic tests revealed 16 Korean patients (94.1%) had RS1 mutations. In one patient, neither sequence variation nor deletion or duplication in RS1 was detected. One case with de novo mutation was confirmed by familial analysis. Identified were 14 causative mutations, three of which were novel: one missense mutation (c.227T>G, p.V76G) and two splice-site mutations (c.78+1G>T and c.78+5G>A). No obvious genotype-phenotype relationship was observed.
A missense mutation was the predominant type, and common or founder mutations were not observed in the Korean patients in this study who had XLRS. This study provides molecular genetic characteristics about an Asian population previously unexplored. The genetic characteristics of Korean XLRS will be helpful for understanding the worldwide spectrum of RS1 mutation.
Citrin is a liver-type mitochondrial aspartate-glutamate carrier encoded by the SLC25A13 gene, and its deficiency causes adult-onset type II citrullinemia and neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD). Here, the authors investigated clinical findings in Korean infants with NICCD and performed mutation analysis on the SLC25A13 gene. Of 47 patients with neonatal cholestasis, three infants had multiple aminoacidemia (involving citrulline, methionine, and arginine) and galactosemia, and thus were diagnosed as having NICCD. Two of these three showed failure to thrive. The laboratory findings showed hypoproteinemia and hyperammonemia, and liver biopsies revealed micro-macrovesicular fatty liver and cholestasis. The three patients each harbored compound heterozygous 1,638-1,660 dup/ S225X mutation, compound heterozygous 851del4/S225X mutation, and heterozygous 1,638-1,660 dup mutation, respectively. With nutritional manipulation, liver functions were normalized and catch-up growth was achieved. NICCD should be considered in the differential diagnosis of cholestatic jaundice in Korean infants.
Cholestasis; Citrin; Citrullinemia; SLC25A13; Mutation
The expression of natriuretic peptides in the neural bundles of the anterior portion of the optic nerves and their functions in regulating vessel tone and blood flow may suggest a possible role in the pathogenesis of glaucoma. The purpose of this study was to investigate the association between normal-tension glaucoma and the genetic variations of atrial natriuretic peptide (Nppa) and natriuretic peptide receptor A (Npr1) gene.
Sixty-seven Korean normal-tension glaucoma (NTG) patients and 100 healthy subjects (as normal controls) were enrolled. DNA from peripheral blood leukocytes was extracted, and the genotypes of five polymorphisms (c.94G>A, c.454T>C, IVS1+16C>T, IVS2+701G>A, and c.-764C>G) in the Nppa gene and one polymorphism (c.1023G>C) in the Npr1 gene were determined using the restriction fragment length polymorphism and the SNaPshot methods. The genotype and allele frequencies of these polymorphisms in patients with NTG and normal controls were compared using the Fisher's exact test and the chi-square test.
In both groups, the genotype distributions were in accordance with the Hardy-Weinberg equilibrium. There was no significant difference in the frequency of the Nppa and Npr1 alleles or genotypes in the normal-tension glaucoma group as compared to the control group.
Nppa and Npr1 gene polymorphisms are not associated with normal-tension glaucoma, suggesting that this gene does not have an important role in the pathogenesis of optic neuropathy in this disease.
Atrial natriuretic peptide; Natriuretic peptide receptor A; Normal-tension glaucoma; Single nucleotide polymorphism