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N-methyl-D-aspartate receptors (NMDARs), a subtype of glutamate-gated ion channels, play a central role in epileptogenesis. Recent studies have identified an increasing number of GRIN2A (a gene encoding the NMDAR GluN2A subunit) mutations in patients with epilepsy. Phenotypes of GRIN2A mutations include epilepsy-aphasia disorders and other epileptic encephalopathies, which pose challenges in clinical treatment. Here we identified a heterozygous GRIN2A mutation (c.1341T>A, p.N447K) from a boy with Rolandic epilepsy by whole-exome sequencing. The patient became seizure-free with a combination of valproate and lamotrigine. Functional investigation was carried out using recombinant NMDARs containing a GluN2A-N447K mutant that is located in the ligand-binding domain of the GluN2A subunit. Whole-cell current recordings in HEK 293T cells revealed that the N447K mutation increased the NMDAR current density by ~1.2-fold, enhanced the glutamate potency by 2-fold, and reduced the sensitivity to Mg inhibition. These results indicated that N447K is a gain-of-function mutation. Interestingly, alternative substitutions by alanine and glutamic acid at the same residue (N447A and N447E) did not change NMDAR function, suggesting a residual dependence of this mutation in altering NMDAR function. Taken together, this study identified human GluN2A N447K as a novel mutation associated with epilepsy and validated its functional consequences in vitro. Identification of this mutation is also helpful for advancing our understanding of the role of NMDARs in epilepsy and provides new insights for precision therapeutics in epilepsy.

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Objective To screen the GABRG2 gene in Chinese patients diagnosed as having epilepsy with febrile seizures plus (EFS+) and analyze the in vitro splicing of intron mutations of GABRG2 gene. Methods After collecting the blood samples from patients with EFS+, all 9 coding exons and introns relevant to mRNA splice of GA BRG2 gene were sequenced by PCR. PCR products of exons 7, 8 and 9 and part of the introns of both ends of GABRG2 gene were cloned into the pTARGET vector to construct pTARGET-Exon-7-8-9 minigene vector and its Exon8+45C>T mutation vector.Wild-type and Exon8+45C>T mutation vector were transfected into HEK 293 cells and extracted RNA for RT-PCR. Results We did not detect mutation in GABRG2 gene coding region, but found 1 mutation in intron Exon8+45C>T. After splicing, the size of RT-PCR products of Wild-type and Exon8+45 OT mutation were both 522 bp. Conclusion Mutations in GABRG2 gene coding region are not likely to be substantially involved in the etiology of EFS+. Exon8+45C>T mutation does not affect the splicing of GABRG2 gene.

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Objective To investigate the association between cutaneous adverse drug reactions (CADRs) caused by antiepileptic drugs and HLA-B*1502 allele. Methods In 31 epileptic patients presented to the Epilepsy Clinic of the Second Affiliated Hospital of Guangzhou Medical College between January 2007 and May 2008, 13 had CADR to carbanazepine (CBZ) including 6 with Stevens-Johnson syndrome (SJS) and 7 with mild maculopapular exanthona (MPE);15 were CBZ-tolerant, and 3 had lamotrigine (LTG)-indueed MPE. All the patients underwent examinations using polymerase chain reaction with sequence specific palmers to analyze HLA -B*1502 allele frequencies, with 30 healthy subjects without a history of using CBZ or LTG as the control. Results HLA-B*IS02 allele frequency was 100% (6/6) in patients with CBZ-SJS, 57% (4/7) in patients with CBZ-induced MPE, and 33% (1/3) in patients with LTG-induced MPE. The frequency was 7% (1/15) in CBZ-tolerant patients and 10% (3/30) in the control subjects. Compared with the CBZ-tolerant patients and the control subjects, the patients with CBZ-induced SJS and MPE had significantly increased HLA -B*1502 allele frequency (P<0.05). Conclusions HLA-B*1502 allele is associated with CADRs to CBZ in epileptic patients.

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Objective To study the clinical features and genetic mechanism of myoclonic-astafic epilepsy (MAE) in infancy. Methods This study was conducted among 10 infants with MAE (including 7 male and 3 female patients) diagnosed between 2006 and 2008 according to the criteria of International League Against Epilepsy (2001). The clinical data including onset age, seizure type, physical signs, EEG, brain maguetic resonance imaging (MRI), effects of anti-epileptic drugs and prognosis were analyzed. The mutations of voltage-gated sodium channel subunit type 1 gene (SCN1A gene) were screened by denaturing high performance liquid chromatography and direct sequencing. Results The 10 MAE cases included 8 sporadic cases and 2 with a family history of febrile seizure and epilepsy. The onset age ranged from 5 months to 39 months, and all the MAE patients had multiple generalized seizure types, including myoclonic-atonic, myoclonic, atonic, tonic-clonic and absence seizures. Two patients had myoclonic status epilepticus, and 7 showed mental retardation. All the patients showed normal findings in MRI. SCN1A gene was screened in 8 of the MAE patients, and no mutation was found. Valproate, clonazepam and levetiracetam were effective in these MAE cases. Conclusion MAE is a rare epilepsy syndrome, whose genetic mechanism is still unclear. Valproate, clonazepam and levetiracetam are effective for MAE, which is associated with poor prognosis.

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<p><b>BACKGROUND</b>In our previous study, we found that DAZAP2 was the most significantly down regulated gene when differential screening of complementary DNA (cDNA) chips were used to analyze mRNA isolated from bone marrow mononuclear cells from newly diagnosed multiple myeloma (MM) patients without anticancer treatment. In this study, we observed DAZAP2 mRNA and protein expression in the mononuclear cells from MM bone marrow and investigated its role in the pathogenesis of MM.</p><p><b>METHODS</b>The full-length cDNA of DAZAP2 was cloned and sequenced from mononuclear cells from human bone marrow. The nucleotide and amino acid sequences of DAZAP2 were analyzed using the ClustalW program. A dendrogram was constructed by multiple sequence alignment using ClustalW and amino acid sequence identity/similarity was derived based on comparisons attained using the MegAlign software. The recombinant pEGFP expression vector was constructed and the confocal microscopy was used for the localization of the DAZAP2 protein in transfected COS7 cells. The expression of DAZAP2 mRNA was detected by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) and the expression level of DAZAP2 protein was detected by Western blotting analysis in MM samples.</p><p><b>RESULTS</b>DAZAP2 proteins of vertebrates is highly conserved in evolution. It contains a proline-rich region, several potential SH2 and SH3 domain-binding motifs and a possible protein kinase C (PKC) phosphorylation site. We showed by confocal microscopy that the DAZAP2 protein predominantly resides in the cytoplasm with a discrete pattern of punctuated distribution. The expression of DAZAP2 was not detected in 24 of 36 MM samples by semi-quantitative RT-PCR. In contrast, DAZAP2 expression was detected in all 30 normal controls. The expression level of DAZAP2 protein was assayed by Western blotting analysis, showing a robust down-regulation in MM patients (P < 0.001) that matched with the results of the RT-PCR.</p><p><b>CONCLUSIONS</b>DAZAP2 is downregulated in MM samples and it may be a signal molecule in MM cells. DAZAP2 is involved in the pathogenesis of MM and could be used as a genetic marker for MM.</p>

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