Hee Hwang

Genetic diagnosis of Duchenne and Becker muscular dystrophy using next-generation sequencing technology: comprehensive mutational search in a single platform.

Background Duchenne muscular dystrophy or Becker muscular dystrophy might be a suitable candidate disease for application of next-generation sequencing in the genetic diagnosis because the complex mutational spectrum and the large size of the dystrophin gene require two or more analytical methods and have a high cost. The authors tested whether large deletions/duplications or small mutations, such as point mutations or short insertions/deletions of the dystrophin gene, could be predicted accurately in a single platform using next-generation sequencing technology. Methods A custom solution-based target enrichment kit was designed to capture whole genomic regions of the dystrophin gene and other muscular-dystrophy-related genes. A multiplexing strategy, wherein four differently bar-coded samples were captured and sequenced together in a single lane of the Illumina Genome Analyser, was applied. The study subjects were 25 patients: 16 with deficient dystrophin expression without a large deletion/duplication and 9 with a known large deletion/duplication. Results Nearly 100% of the exonic region of the dystrophin gene was covered by at least eight reads with a mean read depth of 107. Pathogenic small mutations were identified in 15 of the 16 patients without a large deletion/duplication. Using these 16 patients as the standard, the authors method accurately predicted the deleted or duplicated exons in the 9 patients with known mutations. Inclusion of non-coding regions and paired-end sequence analysis enabled accurate identification by increasing the read depth and providing information about the breakpoint junction. Conclusions The current method has an advantage for the genetic diagnosis of Duchenne muscular dystrophy and Becker muscular dystrophy wherein a comprehensive mutational search may be feasible using a single platform.

New antiepileptic drugs in pediatric epilepsy

New antiepileptic drugs (AEDs), introduced since 1993, provide more diverse options in the treatment of epilepsy. Despite the equivalent efficacy and better tolerability of these drugs, more than 25% of patients remain refractory to treatment. Moreover, the issues for pediatric patients are different from those for adults, and have not been addressed in the development and application of the new AEDs. Recently published evidence-based treatment guidelines have helped physicians to choose the most reasonable AED, although they cannot fully endorse new AEDs because of the lack of well-designed, randomized controlled trials. We review the mechanisms of action, pharmacokinetic properties, adverse reactions, efficacy, and tolerability of eight new AEDs (felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, topiramate, vigabatrin, and zonisamide), focusing on currently available treatment guidelines and expert opinions regarding pediatric epilepsy.

Diagnostic performance of 18F-FDG PET and ictal 99mTc-HMPAO SPET in pediatric temporal lobe epilepsy: Quantitative analysis by statistical parametric mapping, statistical probabilistic anatomical map, and subtraction ictal SPET

We investigated the diagnostic performance of 18F-FDG PET and ictal (99m)Tc-HMPAO SPET in pediatric temporal lobe epilepsy (TLE). Twenty-one pediatric TLE patients were enrolled in this study. Their diagnoses were confirmed by histology and post-surgical outcome (Engel class I or II). The patients ages were 18 or younger (15+/-3 years). Of the 21 patients, 21 patients underwent 18F-FDG PET scan and 15 underwent ictal (99m)Tc-HMPAO SPET. Preoperative PET and/or ictal SPET images were reviewed by simple visual assessment and by statistical parametric mapping (SPM). Asymmetric indices (AI) were calculated using statistical probabilistic anatomical map (SPAM) on 18F-FDG PET. In nine patients who underwent both ictal and interictal SPET, SISCOM (subtraction ictal SPET coregistered to MR template) was performed. PET correctly localized epileptogenic zones in 20 of 21 (95%) by visual assessment. SPM analysis of PET correctly localized epileptogenic zones in 18 of 21 (86%). Ictal SPET correctly localized epileptogenic zones in 12 of 15 (80%) by visual assessment. SPM analysis of ictal SPET correctly localized epileptogenic zones in 12 of 15 (80%). SISCOM correctly localized 8 of 9 (89%), which was equal to that of visual assessment of ictal SPET. The AIs of the temporal lobes by PET were -15+/-8.4 in the left and 9.9+/-8.9 in the right TLE (normal control: -2.9+/-2.8), and correctly localized epileptogenic zones in all cases. As is found in adult TLE, PET and ictal SPET efficiently localized epileptogenic zones in pediatric TLE. SPM analysis of PET or ictal SPET could be used as an aid to visual assessment. Moreover, SISCOM was equal visual assessment of ictal SPET images in terms of lesion localizations.

Relapsing demyelinating CNS disease in a Korean pediatric population: Multiple sclerosis versus neuromyelitis optica

Background and Objective:Our objective was to characterize the clinical and radiologic features of Korean pediatric patients with relapsing central nervous system (CNS) demyelination disease. Methods:Twenty-one patients with relapsing CNS demyelinating events were classified as having multiple sclerosis (MS, 18 patients) or neuromyelitis optica (NMO, three patients) according to the international consensus definitions. Retrospective analysis of clinical and radiologic features was conducted. Anti-aquaporin-4 antibody (AQP4 Ab) test was performed in six patients (including three NMO patients) who showed selective involvement of optic nerve and spinal cord. Results: Median age at the initial episode in patients with MS was 7.0 years (range, 4.4–13.6 years). Three of 18 MS patients (3/18, 17%) showed selective involvement of the optic nerve and spinal cord during the clinical course. Five patients (31%) at the initial episode and nine patients (50%) at relapse met the McDonald magnetic resonance imaging criteria for dissemination in space. Oligoclonal bands detected with a silver staining method were positive in only one patient of 16 patients tested. Two NMO patients positive for AQP4 Ab showed frequent relapses and early disabilities that were unresponsive to interferon treatment. Conclusions:We conclude that Korean pediatric patients with relapsing CNS demyelination disease were characterized by preferential involvement of the optic nerve or spinal cord. The AQP4 Ab test seems to be useful for predicting clinical courses in the setting of heterogeneous opticospinal presentations.

Pantothenate kinase-associated neurodegeneration in Korea: recurrent R440P mutation in PANK2 and outcome of deep brain stimulation

Background and Purpose:u2002 The purpose of this study was to evaluate the mutation status of PANK2 among Korean patients with pantothenate kinase‐associated neurodegeneration (PKAN) and to document the outcome of pallidal deep brain stimulation (DBS).

Noninvasive Prenatal Diagnosis of Duchenne Muscular Dystrophy: Comprehensive Genetic Diagnosis in Carrier, Proband, and Fetus

BACKGROUNDnNoninvasive prenatal diagnosis of monogenic disorders using maternal plasma and targeted massively parallel sequencing is being investigated actively. We previously demonstrated that comprehensive genetic diagnosis of a Duchenne muscular dystrophy (DMD) patient is feasible using a single targeted sequencing platform. Here we demonstrate the applicability of this approach to carrier detection and noninvasive prenatal diagnosis.nnnMETHODSnCustom solution-based target enrichment was designed to cover the entire dystrophin (DMD) gene region. Targeted massively parallel sequencing was performed using genomic DNA from 4 mother and proband pairs to test whether carrier status could be detected reliably. Maternal plasma DNA at varying gestational weeks was collected from the same families and sequenced using the same targeted platform to predict the inheritance of the DMD mutation by their fetus. Overrepresentation of an inherited allele was determined by comparing the allele fraction of 2 phased haplotypes after examining and correcting for the recombination event.nnnRESULTSnThe carrier status of deletion/duplication and point mutations was detected reliably through using a single targeted massively parallel sequencing platform. Whether the fetus had inherited the DMD mutation was predicted correctly in all 4 families as early as 6 weeks and 5 days of gestation. In one of these, detection of the recombination event and reconstruction of the phased haplotype produced a correct diagnosis.nnnCONCLUSIONSnNoninvasive prenatal diagnosis of DMD is feasible using a single targeted massively parallel sequencing platform with tiling design.

Lacosamide as an adjunctive therapy in pediatric patients with refractory focal epilepsy.

PURPOSEnTo evaluate the efficacy and safety of lacosamide in pediatric patients with refractory focal epilepsy.nnnMETHODSnWe reviewed retrospectively the medical records of children younger than 18 years of age treated at Seoul National University Bundang Hospital, in whom oral lacosamide was used as an adjunctive treatment for refractory focal epilepsy. Clinical information regarding the patients epilepsy and the outcome of lacosamide treatment was gathered and analyzed.nnnRESULTSnTwenty-one patients (16 boys, 5 girls) were included, with a median age of 13.9 (range, 1.2-17.9) years. The mean number of concomitant antiepileptic drugs was 3.0 (range, 1-6) and the mean duration of follow-up was 10.1 (range, 6.1-13.0) months. The mean maintenance dose of lacosamide was 5.4 (range, 1.4-9.8) mg/kg/day. Fourteen patients (67%) were responders; four of these were seizure free at the last follow-up. Seven patients (33%) were nonresponders: two of these presented with <50% seizure reduction and five showed no change in seizure frequency. Two patients (10%) discontinued oral lacosamide because of adverse events (aggressive behavior and depression). Mild transient treatment-related adverse events were observed in eight of the 21 patients (38%).nnnCONCLUSIONSnLacosamide represents a useful drug that is effective for a wide range of pediatric refractory focal epilepsy and is well tolerated.

Mutations in ND Subunits of Complex I Are an Important Genetic Cause of Childhood Mitochondrial Encephalopathies

An increasing number of reports on mitochondrial DNA coding regions mutations, especially in mitochondrial DNA— encoded NADH dehydrogenase (ND) subunit genes of the respiratory chain complex I, have been published recently, making it possible to improve the molecular diagnosis of many mitochondrial diseases in children with variable clinical features. This article describes 2 mitochondrial DNA mutations in the ND3 and ND5 genes in patients showing clinical features of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS)/Leigh syndrome overlap syndrome and atypical Leigh syndrome. These cases add to the increasing number of reports stating that mitochondrial DNA—encoded protein-coding regions are mutation hot spots in pediatric patients with encephalopathies with variable clinical spectra.

Long-term effectiveness of ethosuximide, valproic acid, and lamotrigine in childhood absence epilepsy

PURPOSEnWe performed this study to evaluate the long-term efficacy and tolerability of ethosuximide (ESX), valproic acid (VPA), and lamotrigine (LTG) as initial monotherapies for patients with newly diagnosed childhood absence epilepsy.nnnMETHODSnWe retrospectively reviewed the medical records of 128 patients (45 boys and 83 girls) diagnosed with childhood absence epilepsy at the Seoul National University Hospital. The diagnosis was based on the criteria proposed by Panayiotopoulos in 2005. We measured the seizure-free rate and the retention rate observed during 2 years of treatment. Follow-up electroencephalography (EEG), any reported adverse events, and reasons for antiepileptic drug (AED) discontinuation were reviewed.nnnRESULTSnThe seizure-free rate of ESX (84%) was significantly higher than that of VPA (62%) and LTG (53%) at 3 months. The seizure-free rate of ESX (90%) was significantly higher than that of LTG (63%) at 6 months. After 9 months, there was no significant difference in seizure-free rate among the three groups. There were no significant differences among the three groups in terms of normalization of EEG at 12 months (ESX, 77%; VPA, 83%; and LTG, 64%), retention rate throughout the whole treatment period, and adverse-event rates (ESX, 25%; VPA, 29%; and LTG, 14%).nnnCONCLUSIONnThis study suggests that ESX, VPA, and LTG are equally effective in the long-term treatment of newly diagnosed CAE patients. However, the onset of efficacy was faster for ESX compared with VPA or LTG. Efficacy, tolerability, and adverse event profiles should be carefully considered when selecting AEDs to treat individual patients with CAE.

Influence of MECP2 gene mutation and X-chromosome inactivation on the Rett syndrome phenotype

To date, approximately 200 different mutations in the MECP2 gene have been identified. We analyzed the entire coding sequence of the MECP2 gene and the X-chromosome inactivation pattern in 42 sporadic cases of Rett syndrome. Of the 42 patients, 30 had pathogenic mutations, including 14 different mutations: 9 missense mutations, 4 nonsense mutations, and 1 frameshift mutation. One was a novel mutation (S134P). There was a tendency for patients who had a nonsense mutation in the transcriptional repression domain region to show earlier onset of regression and more severe language retardation than patients with a mutation in the methyl-CpG binding domain region. However, the parameters of clinical severity were variable among patients with the same type of mutation, depending on the pattern of X-chromosome inactivation. This study suggests that the X-chromosome inactivation pattern can modify the phenotype of Rett syndrome, which is primarily determined by the type and site of MECP2 gene mutation. ( J Child Neurol 2004;19:503—508).To date, approximately 200 different mutations in the MECP2 gene have been identified. We analyzed the entire coding sequence of the MECP2 gene and the X-chromosome inactivation pattern in 42 sporadic cases of Rett syndrome. Of the 42 patients, 30 had pathogenic mutations, including 14 different mutations: 9 missense mutations, 4 nonsense mutations, and 1 frameshift mutation. One was a novel mutation (S134P). There was a tendency for patients who had a nonsense mutation in the transcriptional repression domain region to show earlier onset of regression and more severe language retardation than patients with a mutation in the methyl-CpG binding domain region. However, the parameters of clinical severity were variable among patients with the same type of mutation, depending on the pattern of X-chromosome inactivation. This study suggests that the X-chromosome inactivation pattern can modify the phenotype of Rett syndrome, which is primarily determined by the type and site of MECP2 gene mutation.