Hiroyuki Torisu

Genetic susceptibility to simple febrile seizures: Interleukin-1β promoter polymorphisms are associated with sporadic cases

Febrile seizures (FSs) are the commonest form of convulsions. A genetic predisposition to FSs is known, based on family studies, twin studies, and complex segregation analysis. Simple FSs may be more homogenous in their clinical manifestations, and show better agreement with the multifactorial inheritance theory than the complex type. Interleukin-1 (IL-1) beta is one of the pro-inflammatory cytokines that are postulated to be involved in the development of FSs. To determine whether or not function-related polymorphisms of the IL-1beta (IL1B) gene are associated with susceptibility to simple FSs, the genotypes for two biallelic polymorphisms in the promoter region at positions -31 and -511 of the IL1B gene were determined by means of PCR-restriction fragment length polymorphism in 229 FS patients (108 sporadic and 60 familial simple FS, and 61 complex FS patients) and 158 controls. IL1B -31C/T, a TATA box polymorphism, has been found to be in complete linkage disequilibrium with the IL1B -511C/T polymorphism. Sporadic simple FS patients exhibited significantly higher frequencies of IL1B -31C/-511T alleles and homozygotes than controls (uncorrected p = 0.0094 and 0.0029, corrected p = 0.038 and 0.035, respectively), while no differences were observed in patients with all or familial simple FSs versus controls. There were no significant differences in the frequencies of -31C/T and -511C/T in the IL-1beta promoter gene between complex FS patients and controls. The present study suggests that the IL-1beta gene contributes to a genetic susceptibility to the development of simple FSs of sporadic occurrence.

Clinical study of childhood acute disseminated encephalomyelitis, multiple sclerosis, and acute transverse myelitis in Fukuoka Prefecture, Japan.

Acute disseminated encephalomyelitis (ADEM) has recently been studied in several countries owing to the development and wide spread use of imaging technology, but few epidemiological studies of childhood ADEM have been undertaken in Asian countries. To perform a comprehensive survey of ADEM and related diseases in Japanese children, we conducted a multicenter, population-based study on childhood ADEM, multiple sclerosis, and acute isolated transverse myelitis in Fukuoka Prefecture, Japan. We identified 26 children with ADEM, 8 with multiple sclerosis, and 4 with acute transverse myelitis during 5 years between September 1998 and August 2003. The incidence of childhood ADEM under the age of 15 years was 0.64 per 100,000 person-years, mean age at onset was 5.7 years, and male-female ratio was 2.3:1. The prevalence of childhood multiple sclerosis was 1.3 per 100,000 persons. The mean age at onset of multiple sclerosis, 9.3 years, was significantly higher than that of ADEM. Nineteen (73%) and four (15%) patients with ADEM experienced antecedent infectious illnesses and vaccinations, respectively, within 1 month before the onset. Clinical and radiological findings of ADEM revealed that the frequency of seizures, mean white blood cell counts in cerebrospinal fluid, and the frequency of subcortical lesions in Fukuoka study, seemed to be higher than those in previous non-Asian studies. These findings suggest that there are ethnic or geographical differences in the incidence and clinical features of ADEM, and that there might be potent genetic or environmental risk factors for ADEM distinct from those for multiple sclerosis.

Functional MxA promoter polymorphism associated with subacute sclerosing panencephalitis

Background: The antivirally active MxA protein is induced by interferon (IFN) α/β and inhibits the replication of single-stranded RNA viruses including measles virus (MV). The authors investigated whether the MxA gene contributed to the development of subacute sclerosing panencephalitis (SSPE) in Japanese individuals. Methods: Single-nucleotide polymorphisms (SNP) in the promoter region of the MxA gene were screened, association studies were performed between two SNP and SSPE, and then a functional difference in the promoter activities of the two SNP was investigated by a dual luciferase reporter assay. Results: Four SNP were found (−88 G/T, −123 C/A, −200 T/C, and −213 G/T), and SSPE patients exhibited a higher frequency of both the −88T allele and the −88TT genotype than controls (p = 0.040 and 0.003). The IFN-induced up-regulation of the MxA promoter activity of the sequence with −88T was found to be significantly higher than that with G. Conclusions: MxA promoter −88 G/T SNP may confer host genetic susceptibility to SSPE in Japanese individuals. The finding that homozygotes of the MxA −88T allele with a high MxA-producing capability were more frequently seen in SSPE patients suggests that the MxA protein promotes the establishment of persistent MV infection of neural cells.

Association of toll-like receptor 3 gene polymorphism with subacute sclerosing panencephalitis

Innate immunity plays an important role in measles virus (MV) infection. MV-derived double-stranded RNA is recognized by toll-like receptor 3 (TLR3), retinoic acid-inducible protein I (RIG-I) and melanoma differentiation—associated gene 5 (MDA5). We investigated whether genes encoding these molecules contributed to the development of subacute sclerosing panencephalitis (SSPE) in Japanese individuals. Four single nucleotide polymorphisms (SNPs) of the three genes (TLR3 rs3775291:Leu412Phe, RIG1 rs277729 and rs9695310, and MDA5 rs4664463) were assessed in 40 SSPE patients and 84 controls. Because the TLR3 SNP showed a positive association with SSPE, three additional SNPs were subjected to haplotype analysis. The frequency of 412Phe allele of TLR3 rs3775291 in SSPE patients was significantly higher than that in controls (P=.03). In haplotype analysis of four SNPs in the TLR3 gene, the frequency of −7C/IVS3 +71C/Phe412/c.1377C haplotype was significantly increased in SSPE patients (P=.006, odds ration [OR]: 2.2). TLR3 gene may confer host genetic susceptibility to SSPE in Japanese individuals.

Moyamoya disease susceptibility gene RNF213 links inflammatory and angiogenic signals in endothelial cells

Moyamoya disease (MMD) is a cerebrovascular disorder characterized by occlusive lesions of the circle of Willis. To date, both environmental and genetic factors have been implicated for pathogenesis of MMD. Allelic variations in RNF213 are known to confer the risk of MMD; however, functional roles of RNF213 remain to be largely elusive. We herein report that pro-inflammatory cytokines, IFNG and TNFA, synergistically activated transcription of RNF213 both in vitro and in vivo. Using various chemical inhibitors, we found that AKT and PKR pathways contributed to the transcriptional activation of RNF213. Transcriptome-wide analysis and subsequent validation with quantitative PCR supported that endogenous expression of cell cycle-promoting genes were significantly decreased with knockdown of RNF213 in cultured endothelial cells. Consistently, these cells showed less proliferative and less angiogenic profiles. Chemical inhibitors for AKT (LY294002) and PKR (C16) disrupted their angiogenic potentials, suggesting that RNF213 and its upstream pathways cooperatively organize the process of angiogenesis. Furthermore, RNF213 down-regulated expressions of matrix metalloproteases in endothelial cells, but not in fibroblasts or other cell types. Altogether, our data illustrate that RNF213 plays unique roles in endothelial cells for proper gene expressions in response to inflammatory signals from environments.

Interleukin-10 is associated with resistance to febrile seizures: Genetic association and experimental animal studies

Purpose:  Febrile seizures (FS) are the most common form of childhood convulsions. Many reports have shown that a proinflammatory cytokine, interleukin‐1 (IL‐1) β, may have a facilitatory effect on the development of FS. We have previously shown that the IL1B ‐511C/T single nucleotide polymorphism (SNP) is associated with simple FS of sporadic occurrence. The balance between pro‐ and antiinflammatory cytokines influences the regulation of infections and could, therefore, play a role in the pathogenesis of FS. Here, to determine whether pro‐ and antiinflammatory cytokine genes are responsible for the susceptibility to FS, we have performed an association study on functional SNPs of cytokine genes in FS patients and controls.

Genetic susceptibility to febrile seizures: Case-control association studies

OBJECTIVE A genetic predisposition to febrile seizures (FS) has long been recognized. The inheritance appears to be polygenic in small families or sporadic cases of FS encountered in daily clinical practice. To determine whether candidate genes are responsible for the susceptibility to FS, we have performed genetic association studies in FS patients and controls. METHODS The single-nucleotide polymorphisms (SNPs) of genes involved in immune response (interleukin (IL) 1B), endocannabinoid signaling (CNR1), acid-base balance (SLC4A3, SLC9A1, SLC9A3), gap junction channel (CX43), and GABA(A) receptor trafficking (PRIP1) were examined in 249 FS patients (186 simple and 63 complex FS) and 225 controls. RESULTS There were no significant differences in the allele frequencies of the SNPs between controls and all FS, simple FS, and complex FS patients. When the simple FS patients were divided into two groups according to either having (familial) or not having a family history of FS in close relatives (sporadic), there was a significant association between IL1B -511 SNP and sporadic simple FS (p=0.003). CONCLUSIONS These data suggest that cytokine genes may act as enhancers or attenuators of FS susceptibility. Genetic association study may be an effective approach to understanding the molecular basis of FS at least in a subgroup of patients.

PD1 as a common candidate susceptibility gene of subacute sclerosing panencephalitis

Although the exact pathogenesis of subacute sclerosing panencephalitis (SSPE) remains to be determined, our previous data suggested a genetic contribution to the host susceptibility to SSPE. During chronic viral infection, virus-specific cytotoxic T lymphocytes display poor effector functions. Since co-inhibitory molecules are involved in the suppression of T lymphocytes, we investigated whether single nucleotide polymorphisms (SNPs) of genes encoding co-inhibitory molecules contributed to a susceptibility to SSPE. Association studies on a total of 20 SNPs in 8 genes (CTLA4, CD80, CD86, PD1, PDL1, PDL2, BTLA and HVEM) and subsequent haplotype analysis of 4 SNPs in the PD1 genes were performed in Japanese and Filipino SSPE patients and controls. Then, we investigated a functional difference in promoter activity of two haplotypes and compared the expression levels of PD1 between SSPE and controls. The frequency of GCG(C) haplotype of PD1 containing −606G allele was significantly higher in SSPE patients than in controls both in Japanese and in Filipinos. The promoter activity was significantly higher in the construct with −606G allele than in that with −606A allele. The expression levels of PD1 were significantly higher in SSPE patients than in the controls. Our results suggested that the PD1 gene contributed to a genetic susceptibility to SSPE.

Benign convulsion with mild gastroenteritis and benign familial infantile seizure

The authors present Japanese siblings of a 6-year-old girl and a 4-year-old boy, who concurrently experienced convulsions with mild gastroenteritis. These siblings, their father and paternal grandfather had afebrile seizures that intermittently occurred without symptoms of gastroenteritis and terminated within a few days at their infancy. An underlying genetic factor might not only cause benign familial infantile seizures but it might also confer the susceptibility to the convulsions with mild gastroenteritis in these siblings.

Founder effect of the C9 R95X mutation in Orientals.

A nonsense mutation at codon 95 (R95X) in the C9 gene is responsible for most Japanese C9 deficiency (C9D) cases, with a carrier frequency of 6.7%. Upon analysis of microsatellite markers and newly identified dinucleotide repeat number polymorphisms in the 3′ flanking region of the C9 gene, a founder effect was demonstrated for the R95X mutation of the C9 gene in Japanese. Screening for the R95X mutation in Korean and Chinese individuals showed that the R95X carrier frequencies in Koreans and Chinese were 2.0% and 1.0%, respectively. Although homozygotes for the R95X mutation were not found in Korea or China, the shared haplotype of the dinucleotide repeat number polymorphisms appeared to be associated with the R95X mutation in the heterozygotes in Korea and China. The founder effect found in East Asians (Japanese, Koreans and Chinese) but not in Caucasians, as well as the haplotype sharing in only a small chromosomal interval, suggested that the R95X mutation of C9 gene was ancient and had occurred after the divergence of East Asians and Caucasians, and before migration of the Yayoi people to Japan. Since the mortality of meningococcal infections in complement-deficient patients is lower than that in normal individuals, a founder effect and a selective advantage in isolation might be the main reasons for the high frequency of the R95X mutation in Japan.