Genetic analysis using targeted exome sequencing of 53 Vietnamese children with developmental and epileptic encephalopathies.

Developmental and epileptic encephalopathies (DEE) refers to a group of rare and severe neurodevelopmental disorders where genetic etiologies can play a major role. This study aimed to elucidate the genetic etiologies of a cohort of 53 Vietnamese patients with DEE. All patients were classified into known electroclinical syndromes where possible. Exome sequencing (ES) followed by a targeted analysis on 294 DEE-related genes was then performed. Patients with identified causative variants were followed for 6 months to determine the impact of genetic testing on their treatment. The diagnostic yield was 38.0% (20/53), which was significantly higher in the earlier onset group (<12 months) than in the later onset group (≥12 months). The 19 identified variants belonged to 11 genes with various cellular functions. Genes encoding ion channels especially sodium voltage-gated channel were the most frequently involved. Most variants were missense variants and located in key protein functional domains. Four variants were novel and four had been reported previously but in different phenotypes. Within 6 months of further follow-up, treatment changes were applied for six patients based on the identified disease-causing variants, with five patients showing a positive impact. This is the first study in Vietnam to analyze the genetics of DEE. This study confirms the strong involvement of genetic etiologies in DEE, especially early onset DEE. The study also contributes to clarify the genotype-phenotype correlations of DEE and highlights the efficacy of targeted ES in the diagnosis and treatment of DEE.

De novo homozygous variant of the SCN1A gene in a patient with severe Dravet syndrome complicated by acute encephalopathy.

Variants in the SCN1A gene have been identified in epilepsy patients with widely variable phenotypes and they are generally heterozygous. Here, we report a homozygous missense variant, NM_001165963.4: c.4319C>T (p.Ala1440Val), in the SCN1A gene which seemed to occur de novo together with a gene conversion event. It's highly possible that this variant, although located in a critical functional domain of protein Nav1.1, depending on the nature of the amino acid substitution, may not cause the complete loss of protein function. And the accumulated effect by having this variant on both alleles results in a Dravet syndrome phenotype which is more severe than average. This first report of a de novo homozygous variant in the SCN1A gene, therefore, provides a clear illustration of a complex genotype-phenotype relationship.

A mutation in GABRB3 associated with Dravet syndrome.

Dravet syndrome is a rare and severe type of epilepsy in infants. Approximately, 70-80% of patients with Dravet syndrome have mutations in SCN1A, the gene encoding the alpha-1 subunit of the sodium channel, while some simplex patients have variants in one of several other genes, including but not limited to GABRA1, SCN2A, STXBP1, GABRG2, and SCN1B. In this study, we performed exome sequencing in six patients with SCN1A-negative Dravet syndrome to identify other genes related to this disorder. In one affected individual, we detected a novel de novo heterozygous missense variant, c.695G>A, p.(Arg232Gln), in GABRB3, the gene encoding the ß3-subunit of the gamma-aminobutyric acid type A (GABAA) receptor, which mediates inhibitory signaling within the central nervous system. In summary, the data in this study identify GABRB3 as a candidate gene for Dravet syndrome.

Differential effect of prior influenza infection on alveolar macrophage phagocytosis of Staphylococcus aureus and Escherichia coli: involvement of interferon-gamma production.

The influenza A virus is one of the main causes of respiratory infection. Although influenza virus infection alone can result in pneumonia, secondary bacterial infection combined with the virus is the major cause of morbidity and mortality. Interestingly, while influenza infection increases susceptibility to some bacteria, including Streptococcus pneumoniae, Staphylococcus aureus (S. aureus), and Haemophilus influenzae, other bacteria such as Escherichia coli (E. coli) and Klebsiella pneumoniae are not associated with influenza infection. The reason for this discrepancy is not known. In this study, it was found that prior influenza virus infection inhibits murine alveolar macrophage phagocytosis of S. aureus but not of E. coli. Here, the mechanism for this inhibition is elucidated: prior influenza virus infection strongly increases interferon gamma (IFN-γ) production. Furthermore, it was shown that IFN-γ differentially affects alveolar macrophage phagocytosis of S. aureus and E. coli. The findings of the present study explain how influenza virus infection increases susceptibility to some bacteria, such as S. aureus, but not others, and provides evidence that IFN-γ might be a promising target for protecting the human population from secondary bacterial infection by influenza.

One-step multiplex reverse-transcriptase PCR for detecting pandemic (H1N1) 2009 influenza virus.

Pandemic (H1N1) 2009 influenza has spread throughout the world since April 2009 and has caused many human deaths since its first report in humans. Pandemic (H1N1) 2009 influenza virus was first identified in a Canadian pig herd in April 2009 and has been reported in more than ten countries, including Korea. We developed a one-step multiplex reverse transcriptase polymerase chain reaction (RT-PCR) assay based on the matrix gene that discriminates pandemic (H1N1) 2009 influenza virus from endemic swine influenza viruses. The sensitivity of this assay was 100 copies of in vitro-transcribed target RNA and 0.01 tissue culture infective dose (TCID(50)/ml) of virus and was as high as those of conventional influenza A virus common matrix reverse transcriptase PCR assays and real-time reverse transcriptase PCR assays (1 to 200 copies) developed for detecting pandemic (H1N1) 2009 influenza viruses from human and pig samples. This one-step multiplex RT-PCR assay would be a good tool in monitoring pandemic (H1N1) 2009 influenza virus among pig herds on a regular basis.

Effects of red ginseng on the regulation of cyclooxygenase-2 of spleen cells in whole-body gamma irradiated mice.

Exposure to gamma radiation causes a wide range of biological damage and alterations, including oxidative stress, inflammation and cancer. This study aimed to identify the radioprotective effect of Korean red ginseng extract (RG) against whole-body gamma-irradiation (γIR) in mice and the regulatory mechanisms of the radiosensitive gene in spleen, cyclooxygenase-2 (COX-2). RG was administered intraperitoneally (i.p.) or orally (p.o.) to C57BL/6 mice for five days, which were then exposed to 6.5 Gy of (137)Cs-γIR. Thymus and spleen were harvested after three days, and organ size and COX-2 expression of the spleen using Western blotting, were examined. γIR shrank both organs and RG recovered the size of thymus but not spleen. RG also significantly inhibited the increased expression of COX-2 induced by γIR. These results were similar following both routes of RG administration, however i.p. RG administration was more effective, thus it was used in progressive studies. In terms of COX-2 expression related intracellular factors, we found here that γIR activated the p38 MAPK, PI3K/Akt and HO-1 but not NF-κB or Nrf2. Activated p38 MAPK, PI3K/Akt and HO-1 were down-regulated by RG while the RG-induced COX-2 expression was only related to HO-1 activation. These results suggest that RG supplementation provides protective effects against radiation-induced inflammation and cancer, and its potential to be utilized in clinical trials and functional foods.

Involvement of NF-κB in changes of IFN-γ-induced CIITA/MHC-II and iNOS expression by influenza virus in macrophages.

Type II interferon (IFN-γ) plays an important role in defense against viral infection. Although this cytokine is found during influenza virus infection, it seems to have no protective function against the virus, and the reasons for this are not clear. To determine how the influenza virus overcomes the antiviral effects of IFN-γ, we examined the effect of A/Puerto-Rico/8/34 (H1N1) (PR8) infection on the expression of various IFN-γ inducible genes involved in defense against virus infection. The results showed that PR8 selectively affects IFN-γ induced MHC-II and iNOS expression in both the murine macrophage-like cell line, Raw264.7, and in primary alveolar macrophages. Infection of IFN-γ treated macrophages with PR8 resulted in decreased expression of CIITA/MHC-II and increased production of iNOS/NO. These changes correlate with activation of NF-κB but not with JAK/STAT signaling. The data indicate one possible mechanism underlying the ineffectiveness of IFN-γ against influenza virus, and suggest that NF-κB may be a promising target for anti-influenza drugs.