Linkage and association with the NOS2A locus on chromosome 17q11 in multiple sclerosis

Exhaled Nitric Oxide as Biomarker of Type 2 Diseases

Nitric oxide (NO) is a short-lived gas molecule which has been studied for its role as a signaling molecule in the vasculature and later, in a broader view, as a cellular messenger in many other biological processes such as immunity and inflammation, cell survival, apoptosis, and aging. Fractional exhaled nitric oxide (FeNO) is a convenient, easy-to-obtain, and non-invasive method for assessing active, mainly Th2-driven, airway inflammation, which is sensitive to treatment with standard anti-inflammatory therapy. Consequently, FeNO serves as a valued tool to aid the diagnosis and monitoring of several asthma phenotypes. More recently, FeNO has been evaluated in several other respiratory and/or immunological conditions, including allergic rhinitis, chronic rhinosinusitis with/without nasal polyps, atopic dermatitis, eosinophilic esophagitis, and food allergy. In this review, we aim to provide an extensive overview of the current state of knowledge about FeNO as a biomarker in type 2 inflammation, outlining past and recent data on the application of its measurement in patients affected by a broad variety of atopic/allergic disorders.

Understanding the genetics of intracranial aneurysms: A primer

The genetics of intracranial aneurysms is complex. Much work has been done looking at the extracellular matrix surrounding cerebral vasculature as well as the role of matrix metalloproteinases. This comprehensive review summarizes what is known to date about the important genetic components that predispose to aneurysm formation and critically discusses the published findings. We discuss promising pre-clinical models of aneurysm formation and subarachnoid hemorrhage, and highlight avenues for future discovery, while considering limitations in the research to date. This review will further serve as a comprehensive reference guide to understand the genetic underpinnings for aneurysm pathophysiology and act as a primer for further investigation.

The role of nitric oxide in brain disorders: Autism spectrum disorder and other psychiatric, neurological, and neurodegenerative disorders

Nitric oxide (NO) is a multifunctional signalling molecule and a neurotransmitter that plays an important role in physiological and pathophysiological processes. In physiological conditions, NO regulates cell survival, differentiation and proliferation of neurons. It also regulates synaptic activity, plasticity and vesicle trafficking. NO affects cellular signalling through protein S-nitrosylation, the NO-mediated posttranslational modification of cysteine thiols (SNO). SNO can affect protein activity, protein-protein interaction and protein localization. Numerous studies have shown that excessive NO and SNO can lead to nitrosative stress in the nervous system, contributing to neuropathology. In this review, we summarize the role of NO and SNO in the progression of neurodevelopmental, psychiatric and neurodegenerative disorders, with special attention to autism spectrum disorder (ASD). We provide mechanistic insights into the contribution of NO in diverse brain disorders. Finally, we suggest that pharmacological agents that can inhibit or augment the production of NO as well as new approaches to modulate the formation of SNO-proteins can serve as a promising approach for the treatment of diverse brain disorders.

Endothelial nitric oxide synthase (NOS3) rs2070744 polymorphism and risk for multiple sclerosis

The possible role of oxidative stress and nitric oxide (NO) in the pathogenesis of multiple sclerosis (MS) has been suggested by several neuropathological, biochemical, and experimental data. Because the single-nucleotide polymorphism (SNP) rs2070744 in the endothelial nitric oxide synthase (eNOS or NOS3) gene (chromosome 7q36.1) showed association with the risk for MS in Iranians, we attempted to replicate the possible association between this SNP and the risk for MS in the Caucasian Spanish population. The frequencies of NOS3rs2070744 genotypes and allelic variants in 300 patients diagnosed with MS and 380 healthy controls were assessed with a TaqMan-based qPCR assay. The possible influence of the genotype frequency on age at onset of MS, the severity of MS, clinical evolutive subtypes of MS, and HLA-DRB1*1501 genotype were also analyzed. The frequencies of rs2070744 genotypes and allelic variants were not associated with the risk of developing MS and were not influenced by gender, age at onset and severity of MS, the clinical subtype of MS or the HLA-DRB1*1501 genotype. This study found a lack of association between NOS3 rs2070744 SNP and the risk for MS in Caucasian Spanish people.

The combined effects of cardiovascular disease related SNPs on ischemic stroke

PURPOSE

Previous studies have revealed multiple common variants associated with known risk factors for cardiovascular disease (CVD). Ischemic stroke (IS) and CVD share several risk factors with each having substantial heritability. We aimed to generate a multi-locus genetic risk score (GRS) for IS based on CVD related SNPs to evaluate their combined effects on IS.

METHODS

A total of 851 patients and 977 controls were selected from Beijing, Tianjin, Shandong, Shanxi, Shaanxi and Heilongjiang communities. The candidate genes were genotyped by PCR-hybridization. Information about demographic factors, history of disease (such as hypertension), and lifestyle was obtained using structured questionnaires. A GRS model weighted by the absolute value of regression coefficient β was established to comprehensively assess the association between candidate SNPs and IS. Using the area under the receiver operating characteristic curve (AUC) to evaluate the value of GRS on predicting IS.

RESULTS

The GRS of cases was 2.87 ± 0.28, which was significantly higher than controls' GRS (2.78 ± 0.30) (P < 0.000). With the increase of the GRS, the risk of IS became higher (P_trend < 0.000). Subjects in the top quartile of the GRS had about 1.9-fold increased risk of IS compared with subjects in the lowest quartile (OR _adjusted = 1.880, 95%CI = 1.442-2.452, P < 0.000). The AUC = 0.580, P < 0.000.

CONCLUSION

13 CVD related SNPs had combined effects on IS. The GRS of cases was significantly higher than controls' GRS. As the GRS increased, the risk of IS increased. The GRS model has some value for the prediction of IS.

Polymorphisms in oxidative pathway related genes and susceptibility to inflammatory bowel disease

AIM

To investigate whether common variants in the oxidative pathway genes influence inflammatory bowel disease (IBD) risk among Moroccan patients.

METHODS

The distribution of (TAAA)n_rs12720460 and (CCTTT)n _rs3833912 NOS2A microsatellite repeats, HIF-1A_rs11549467 and NFKB1-94ins/delATTG_rs28362491 was analyzed in 507 subjects grouped in 199 IBD and 308 healthy controls. Genotyping was performed with polymerase chain reaction-fluorescent method and the TaqMan^® allelic discrimination technology.

RESULTS

The allele and genotype frequencies of HIF1A_ rs11549467, NFKB1_rs28362491 and NOS2A_ (TAAA)n did not differ significantly between patients and controls. Analysis of NOS2A_ (CCTTT)n markers evidenced differences between patients and healthy controls. A preferential presence of the (CCTTT)8 (P = 0.02; OR = 1.71, 95%CI: 1.07-2.74), (CCTTT)14 (P = 0.02; OR = 1.71, 95%CI: 1.06-2.76) alleles in IBD, (CCTTT)8 (P = 0.008; OR = 1.95, 95%CI: 1.17-3.23) in CD and (CCTTT)7 (P = 0.009; OR = 7.61, 95%CI: 1.25-46.08), (CCTTT)11 (P = 0.05; OR = 0.51, 95%CI: 0.25-1.01), (CCTTT)14 (P = 0.02; OR = 2.05, 95%CI: 1.07-3.94), (CCTTT)15 (P = 0.01; OR = 2.25, 95%CI: 1.16-4.35) repeats in UC patients indicated its possible association with higher disease risk which need to be confirmed in a larger sample size.

CONCLUSION

Our results suggest that the NOS2A_ (CCTTT)n gene variations may influence IBD susceptibility in the Moroccan population.

Association of CVD candidate gene polymorphisms with ischemic stroke and cerebral hemorrhage in Chinese individuals

BACKGROUND

Contribution of cardiovascular disease related genetic risk factors for stroke are not clearly defined. We performed a genetic association study to assess the association of 56 previously characterized gene variants in 34 candidate genes from cardiovascular disease related biological pathways with ischemic stroke and cerebral hemorrhage in a Chinese population.

METHODS

There were 1280 stroke patients (1101 with ischemic stroke and 179 with cerebral hemorrhage) and 1380 controls in the study. The genotypes for 56 polymorphisms of 34 candidate genes were determined by the immobilized probe approach and the associations of gene polymorphisms with ischemic stroke and cerebral hemorrhage were performed by logistic regression under an allelic model.

RESULTS

After adjusting for age, sex, BMI and hypertension status by logistic regression analysis, we found that NPPA rs5063 was significantly associated with both ischemic stroke (odds ratio [OR] 0.69; 95% confidence interval [CI], 0.52 to 0.90; P = 0.006) and cerebral hemorrhage(OR = 0.39; 95%CI, 0.19 to 0.78; P = 0.007). In addition, MTHFR rs1801133 also was associated with cerebral hemorrhage (OR = 1.48; 95%CI, 1.16 to 1.89; P = 0.001) but not with ischemic stroke (OR = 1.08; 95%CI, 0.96 to 1.22; P = 0.210). After false discovery rate (FDR) correction, the association of NPPA rs5063 and MTHFR rs1801133 with cerebral hemorrhage remained significant.

CONCLUSIONS

The NPPA rs5063 is associated with reduced risk for cerebral hemorrhage and MTHFR rs1801133 is associated with increased risk of cerebral hemorrhage in a Chinese population.

Genetic variants in inducible nitric oxide synthase gene are associated with the risk of radiation-induced lung injury in lung cancer patients receiving definitive thoracic radiation

BACKGROUND AND PURPOSE

Nitric oxide (NO), mainly synthesized by inducible nitric oxide synthase (NOS2) in pathological conditions, plays an important role in cytotoxicity, inflammation and fibrosis. Elevations in exhaled NO after thoracic radiation have been reported to predict radiation-induced lung injury (RILI). This study examined whether genetic variations in NOS2 gene is associated with the risk of RILI.

MATERIAL AND METHODS

A cohort of 301 patients between 2009 and 2011 were genotyped for 21 single nucleotide polymorphisms (SNPs) in the NOS2 gene by the Sequenom MassArray system. Kaplan-Meier cumulative probability was used to assess RILI risk and Cox proportional hazards analyses were performed to evaluate the effect of NOS2 genotypes on RILI.

RESULTS

Multivariate analysis found that three SNPs (rs2297518, rs1137933 and rs16949) in NOS2 were significantly associated with risk of RILI⩾2 (P value=0.001, 0.000092, 0.001, respectively) after adjusting for other covariates. Their associations were independent of radiation dose and mean lung dose. Further haplotype analysis indicated that the ATC haplotype of three SNPs is associated with reducing the risk of developing RILI.

CONCLUSION

Our results demonstrate that genetic variants of NOS2 may serve as a reliable predictor of RILI in lung cancer patients treated with thoracic radiation.

Genetic risk variants in African Americans with multiple sclerosis

OBJECTIVES

To assess the association of established multiple sclerosis (MS) risk variants in 3,254 African Americans (1,162 cases and 2,092 controls).

METHODS

Human leukocyte antigen (HLA)-DRB1, HLA-DQB1, and HLA-A alleles were typed by molecular techniques. Single nucleotide polymorphism (SNP) genotyping was conducted for 76 MS-associated SNPs and 52 ancestry informative marker SNPs selected throughout the genome. Self-declared ancestry was refined by principal component analysis of the ancestry informative marker SNPs. An ancestry-adjusted multivariate model was applied to assess genetic associations.

RESULTS

The following major histocompatibility complex risk alleles were replicated: HLA-DRB1*15:01 (odds ratio [OR] = 2.02 [95% confidence interval: 1.54-2.63], p = 2.50e-07), HLA-DRB1*03:01 (OR = 1.58 [1.29-1.94], p = 1.11e-05), as well as HLA-DRB1*04:05 (OR = 2.35 [1.26-4.37], p = 0.007) and the African-specific risk allele of HLA-DRB1*15:03 (OR = 1.26 [1.05-1.51], p = 0.012). The protective association of HLA-A*02:01 was confirmed (OR = 0.72 [0.55-0.93], p = 0.013). None of the HLA-DQB1 alleles were associated with MS. Using a significance threshold of p < 0.01, outside the major histocompatibility complex region, 8 MS SNPs were also found to be associated with MS in African Americans.

CONCLUSION

MS genetic risk in African Americans only partially overlaps with that of Europeans and could explain the difference of MS prevalence between populations.

Genetic and clinical contributions to cerebral palsy: a multi-variable analysis

AIM

This study aims to examine single nucleotide polymorphism (SNP) associations with cerebral palsy in a multi-variable analysis adjusting for potential clinical confounders and to assess SNP-SNP and SNP-maternal infection interactions as contributors to cerebral palsy.

METHODS

A case control study including 587 children with cerebral palsy and 1154 control children without cerebral palsy. Thirty-nine candidate SNPs were genotyped in both mother and child. Data linkage to perinatal notes and cerebral palsy registers was performed with a supplementary maternal pregnancy questionnaire. History of known maternal infection during pregnancy was extracted from perinatal databases.

RESULTS

Both maternal and fetal carriage of inducible nitric oxide synthase SNP rs1137933 were significantly negatively associated with cerebral palsy in infants born at less than 32 weeks gestation after adjustment for potential clinical confounders and correction for multiple testing (odds ratio 0.55, 95% confidence interval 0.38-0.79; odds ratio 0.57, 95% confidence interval 0.4-0.82, respectively). Analysis did not show any statistically significant SNP-SNP or SNP-maternal infection interactions after correction for multiple testing.

CONCLUSIONS

Maternal and child inducible nitric oxide synthase SNPs are associated with reduced risk of cerebral palsy in infants born very preterm. There was no evidence for statistically significant SNP-SNP or SNP-maternal infection interactions as modulators of cerebral palsy risk.

Single nucleotide polymorphisms in inflammation-related genes are associated with venous thromboembolism

BACKGROUND

Various genetic risk factors are known to increase the risk of venous thromboembolism (VTE). Increasing evidence suggests a "cross-talk" between the coagulation and inflammatory cascade. Therefore, polymorphisms in genes involved in inflammation may influence susceptibility towards VTE. The aim of the study was to investigate the role of single nucleotide polymorphisms (SNPs) in inflammation genes for susceptibility towards VTE.

METHODS

The study group consisted of 108 (47 men and 61 women) Dutch patients with documented VTE and 325 healthy controls from the same geographical area (117 men and 208 women). Odds ratios (OR) and 95% confidence intervals (95% CI) for VTE separately and if indicated by gender were calculated to assess whether genotype and allele frequency were associated with thrombosis.

RESULTS

Heterozygosity for SNP -899C/T of the interleukin 1-alpha gene (IL1A -899C/T) was under-represented in VTE patients compared to the control group (OR=0.51, 95% CI 0.32-0.82). The IL6 -174 CC genotype was more frequent in male patients with VTE compared to male controls (OR=4.06, 95% CI 1.43-11.5). Female patients carried significantly more IL13 (intron3) TT genotype (OR=5.60, 95% CI 1.94-18.5) compared to female controls. The allelic frequency of IL4 -589 T allele was significantly increased in female patients (OR=1.72, 95% CI 1.05-2.81) in contrast to men where no differences were observed.

CONCLUSION

Four SNPs in inflammatory-related genes of IL1A, IL4, IL6, and IL13 may be associated with VTE. These results need to be confirmed in independent groups with larger number of patients.

An evaluation of inflammatory gene polymorphisms in sibships discordant for premature coronary artery disease: the GRACE-IMMUNE study

BACKGROUND

Inflammatory cytokines play a crucial role in coronary artery disease (CAD). We investigated the association between 48 coding and three non-coding single nucleotide polymorphisms (SNPs) from 35 inflammatory genes and the development of CAD, using a large discordant sibship collection (2699 individuals in 891 families).

METHODS

Family-based association tests (FBAT) and conditional logistic regression (CLR) were applied to single SNPs and haplotypes and, in CLR, traditional risk factors of CAD were adjusted for.

RESULTS

An association was observed between CAD and a common three-locus haplotype in the interleukin one (IL-1) cluster with P = 0.006 in all CAD cases, P = 0.01 in myocardial infarction (MI) cases and P = 0.0002 in young onset CAD cases (<50 years). The estimated odds ratio (OR) per copy of this haplotype is 1.21 (95% confidence interval [95CI] = 1.04 - 1.40) for CAD; 1.30 (95CI = 1.09 - 1.56) for MI and 1.50 (95CI = 1.22 - 1.86) for young onset CAD. When sex, smoking, hypertension and hypercholesterolaemia were adjusted for, the haplotype effect remained nominally significant (P = 0.05) in young onset CAD cases, more so (P = 0.002) when hypercholesterolaemia was excluded. As many as 82% of individuals affected by CAD had hypercholesterolaemia compared to only 29% of those unaffected, making the two phenotypes difficult to separate.

CONCLUSION

Despite the multiple hypotheses tested, the robustness of family design to population confoundings and the consistency with previous findings increase the likelihood of true association. Further investigation using larger data sets is needed in order for this to be confirmed. See the related commentary by Keavney: http://www.biomedcentral.com/1741-7015/8/6.

Association of 77 polymorphisms in 52 candidate genes with blood pressure progression and incident hypertension: the Women's Genome Health Study

OBJECTIVE

Genetic risk factors for essential hypertension are largely unknown. The aim of the present study was to assess the association of 77 previously characterized gene variants in 52 candidate genes from various biological pathways with blood pressure (BP) progression and incident hypertension.

METHODS

We analyzed data from 18 738 white women who participated in a prospective cohort study and were free of hypertension at baseline. BP progression at 48 months and incident hypertension during the entire follow-up according to the different genotypes were assessed by logistic regression and Cox proportional-hazards models, respectively.

RESULTS

At 48 months of follow-up, 7889 of 16 635 women (47.4%) had BP progression. Only three of 70 polymorphisms with a minor allele frequency of at least 2% had a significant association with BP progression. The odds ratio [95% confidence interval (CI)] for 5,10-methylenetetrahydrofolate reductase (MTHFR) rs1801133 (minor allele T), natriuretic peptide precursor A (NPPA) rs5063 (minor allele A) and NPPA rs5065 (minor allele C) were 1.05 (1.00-1.10), 0.84 (0.76-0.94) and 0.93 (0.88-1.00), respectively. After adjustment for multiple testing using the false discovery rate, only the NPPA rs5063 association remained significant. During a median follow-up of 9.8 years, 5540 of 18 738 women developed incident hypertension. Only five of 70 polymorphisms were significantly associated with incident hypertension. The hazard ratio (95% CI) for interleukin 6 (IL-6) rs1800795 (minor allele C), MTHFR rs1801133, NPPA rs5063, nitric oxide synthase 3 rs1799983 (minor allele T) and transforming growth factor, beta 1 rs1800469 (minor allele T) were 0.96 (0.92-1.00), 1.06 (1.02-1.10), 0.88 (0.80-0.96), 1.05 (1.01-1.09) and 1.05 (1.01-1.10), respectively. After adjustment for multiple testing, none of these associations remained significant.

CONCLUSION

NPPA gene polymorphisms may have a role in BP progression and incident hypertension. Our data also provide moderate confirmatory evidence of association between MTHFR rs1801133 and the development of hypertension.

Variation in the lymphotoxin-alpha/tumor necrosis factor locus modifies risk of erythema nodosum in sarcoidosis

Sarcoidosis is a multi-system inflammatory disease with organ involvement that varies by race and sex. Family studies indicate that genes play a role in the etiology and extent of organ involvement in sarcoidosis. In this study, we evaluated whether 25 variants distributed in 19 genes with a known role in inflammation were associated with erythema nodosum status in 659 sarcoidosis patients and 658 controls from A Case-Control Etiologic Study of Sarcoidosis (ACCESS). We found no association with affectation status; however, a variant in the promoter of tumor necrosis factor (TNF) at position -308 was found to be associated with erythema nodosum in Caucasian sarcoidosis patients (study-wide P=0.027). When separated by sex, a variant in intron 1 of lymphotoxin-alpha (LTA), a gene adjacent to TNF, was associated with erythema nodosum in female Caucasian sarcoidosis patients (study-wide P=0.027). These DNA variants frequently occur together in Caucasians, and each variant has individually been associated with erythema nodosum in sarcoidosis patients. These results confirm that variation in the LTA/TNF gene cluster modifies a major skin manifestation of sarcoidosis and may explain the higher rate of erythema nodosum in females with sarcoidosis.

A meta-analysis of candidate gene polymorphisms and ischemic stroke in 6 study populations: association of lymphotoxin-alpha in nonhypertensive patients

BACKGROUND AND PURPOSE

Ischemic stroke is a multifactorial disease with a strong genetic component. Pathways, including lipid metabolism, systemic chronic inflammation, coagulation, blood pressure regulation, and cellular adhesion, have been implicated in stroke pathophysiology, and candidate gene polymorphisms in these pathways have been proposed as genetic risk factors.

METHODS

We genotyped 105 simple deletions and single nucleotide polymorphisms from 64 candidate genes in 3550 patients and 6560 control subjects from 6 case-control association studies conducted in the United States, Europe, and China. Genotyping was performed using the same immobilized probe typing system and meta-analyses were based on summary logistic regressions for each study. The primary analyses were fixed-effects meta-analyses adjusting for age and sex with additive, dominant, and recessive models of inheritance.

RESULTS

Although 7 polymorphisms showed a nominal additive association, none remained statistically significant after adjustment for multiple comparisons. In contrast, after stratification for hypertension, 2 lymphotoxin-alpha polymorphisms, which are in strong linkage disequilibrium, were significantly associated among nonhypertensive individuals: LTA 252A>G (additive model; OR, 1.41 with 95% CI, 1.20 to 1.65; P=0.00002) and LTA 26Thr>Asn (OR, 1.19 with 95% CI, 1.06 to 1.34; P=0.003). LTA 252A>G remained significant after adjustment for multiple testing using either the false discovery rate or by permutation testing. The 2 single nucleotide polymorphisms showed no association in hypertensive subjects (eg, LTA 252A>G, OR, 0.93; 95% CI, 0.84 to 1.03; P=0.17).

CONCLUSIONS

These observations may indicate an important role of LTA-mediated inflammatory processes in the pathogenesis of ischemic stroke.

Polymorphisms in inflammatory genes and the risk of ischemic stroke and transient ischemic attack: results of a multilocus genotyping assay

BACKGROUND

Single-nucleotide polymorphisms (SNPs) in inflammation-related genes have been linked to an increased risk of ischemic stroke. Most of these SNP results have not been replicated, however, and metaanalyses of the effects of inflammation-related genes are rare. We investigated 49 SNPs in 34 genes previously reported to be related to inflammation in our study. We tested 459 patients with acute ischemic stroke or transient ischemic attack and 459 controls individually matched by sex and age.

METHODS

We studied genetic variation by PCR analysis and subsequent hybridization to linear arrays of sequence-specific oligonucleotides. We used univariate conditional logistic regression analysis to test for associations of conventional vascular risk factors and the SNPs with stroke. Variables showing significant differences (P < 0.05) between cases and controls were included in a multivariate model. ROC curves were plotted to assess the contribution of genetic variation to stroke risk in addition to that of conventional risk factors.

RESULTS

Univariate regression analysis revealed 3 SNPs with significant allelic differences between patients and controls, which fulfilled the criteria for further analysis. Only one of these SNPs, the C5 (complement component 5) 2416A>G variant (rs17611), remained significant after the multivariate analysis (odds ratio, 0.585; P = 0.0037). ROC curve analysis revealed no contribution of this genetic variation to stroke risk.

CONCLUSIONS

We found evidence for an association of the 2416A>G polymorphism in the C5 gene with the risk for ischemic stroke. Our data suggest that the C5 gene particularly influences the risk for patients with microangiopathy.

Identification of novel single nucleotide polymorphisms in inflammatory genes as risk factors associated with trachomatous trichiasis

Background

Trachoma is the leading preventable cause of global blindness. A balanced Th1/Th2/Th3 immune response is critical for resolving Chlamydia trachomatis infection, the primary cause of trachoma. Despite control programs that include mass antibiotic treatment, reinfection and recurrence of trachoma are common after treatment cessation. Furthermore, a subset of infected individuals develop inflammation and are at greater risk for developing the severe sequela of trachoma known as trachomatous trichiasis (TT). While there are a number of environmental and behavioral risk factors for trachoma, genetic factors that influence inflammation and TT risk remain ill defined.

Methodology/Findings

We identified single nucleotide polymorphisms (SNP) in 36 candidate inflammatory genes and interactions among these SNPs that likely play a role in the overall risk for TT. We conducted a case control study of 538 individuals of Tharu ethnicity residing in an endemic region of Nepal. Trachoma was graded according to World Health Organization guidelines. A linear array was used to genotype 51 biallelic SNPs in the 36 genes. Analyses were performed using logic regression modeling, which controls for multiple comparisons. We present, to our knowledge, the first significant association of TNFA (-308GA), LTA (252A), VCAM1 (-1594TC), and IL9 (T113M) polymorphisms, synergistic SNPs and risk of TT. TT risk decreased 5 times [odds ratio = 0.2 (95% confidence interval 0.11.–0.33), p = 0.001] with the combination of TNFA (-308A), LTA (252A), VCAM1 (-1594C), SCYA 11 (23T) minor allele, and the combination of TNFA (-308A), IL9 (113M), IL1B (5′UTR-T), and VCAM1 (-1594C). However, TT risk increased 13.5 times [odds ratio = 13.5 (95% confidence interval 3.3–22), p = 0.001] with the combination of TNFA (-308G), VDR (intron G), IL4R (50V), and ICAM1 (56M) minor allele.

Conclusions

Evaluating genetic risk factors for trachoma will advance our understanding of disease pathogenesis, and should be considered in the context of designing global control programs.

Genetic variation in nitric oxide synthase 2A (NOS2A) and risk for multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disorder of the central nervous system with a strong genetic component. Variation in the major histocompatibility complex on chromosome 6p21, specifically the HLA-DRB1*15 haplotype, is the strongest genetic factor for MS, yet it is estimated to account for only a portion of risk for the disease. Previous evidence has implicated the nitric oxide synthase gene (NOS2A) encoding inducible NOS on chromosome 17q11 as a potential MS susceptibility gene. To determine whether variation in the NOS2A gene contributes to MS risk, we investigated a total of 50 polymorphisms within or flanking the locus for evidence of association using a comprehensive analytical strategy. A total of 6265 members from 1858 well-characterized MS families were utilized. No evidence for overtransmission of any individual single-nucleotide polymorphism allele or haplotype to the MS-affected individuals was observed. Furthermore, different transmission rates were not observed in either DRB1*15-positive or DRB1*15-negative family subgroups, or when extreme clinical outcomes characterizing disease progression were examined. The very largest study of NOS2A variation in MS, to date, excludes even a modest role for this locus in susceptibility.

Multiple sclerosis genetics

Multiple sclerosis (MS) clusters with the so-called complex genetic diseases, a group of common disorders characterized by modest disease risk heritability and multifaceted gene-environment interactions. The major histocompatibility complex (MHC) is the only genomic region consistently associated with MS, and susceptible MHC haplotypes have been identified. Although the MHC does not account for all genetic contribution to MS, the other genetic contributors have been elusive. Microarray gene-expression studies, which also have not identified a major MS locus, have, however, been promising in elucidating some of the possible pathways involved in the disease. Yet, microarray studies thus far have been unable to separate the genetic causes of MS from the expression consequences of MS. The use of new methodologies and technologies to refine the phenotype, such as brain spectroscopy, PET and functional magnetic resonance imaging combined with novel computational tools and a better understanding of the human genome architecture, may help resolve the genetic causes of MS.

Preliminary evidences of a NOS2A protective effect from Relapsing–Remitting Multiple Sclerosis

The gene encoding the inducible form of Nitric Oxide Synthase (NOS2A) has been considered with interest in the evaluation of the genetic predisposition to Multiple Sclerosis (MS). The aim of the present study was to address the possible contribution of two microsatellites repeats of the NOS2A promoter region - (CCTTT)(n) and (AAAT)(n) - to MS susceptibility. One hundred and thirteen Italian patients with clinically definite RRMS and 237 age and sex matched healthy controls from Calabria (South Italy) were studied. The distribution analysis of the markers frequencies showed that the (CCTTT)(14) allele was found in 11.5% of the RRMS patients and in 25.3% of the healthy subjects, with a statistically significant difference (chi(2)=8.843, p=0.003). This data seems to confer a significant protection against MS (OR=0.348; 95% CI=0.174-0.693, corrected for age and gender). No association with MS susceptibility was observed for the bi-allelic (AAAT)(n) microsatellite. In conclusion, we found that the NOS2A (CCTTT)(14) allele was detected more frequently in the control group than in the RRMS patients, thus confirming the scientific interest on this marker.

Influence of the inducible nitric oxide synthase gene (NOS2A) on inflammatory bowel disease susceptibility

The great amount of nitric oxide (NO) produced by the inducible isoform of NO synthase (iNOS) exerts deleterious effects, and iNOS expression is raised in the colonic mucosa of inflammatory bowel disease (IBD) patients. This is the first association analysis of polymorphisms within the NOS2A extended gene with IBD susceptibility. We analyzed 336 patients of Crohn's disease (CD), 355 of ulcerative colitis (UC), and 536 healthy controls from a Spanish population. We tested a (CCTTT)n microsatellite, a (-/TAAA) insertion, and two single nucleotide polymorphisms (SNPs) flanking them (rs2779251 and rs2779248) in the NOS2A promoter, together with two SNPs in the coding region: one within exon 10, D385D (rs1137933), and another mapping to exon 16, S608L (rs2297518). Analysis of these markers evidenced differences among IBD patients and healthy controls. Allele (CCTTT) 13 is related to higher UC risk (p = 0.001; odds ratio [OR] [95% confidence interval, CI] = 1.64 [1.20-2.23]). Carriers of minor alleles of the two promoter SNPs analyzed showed an association with UC predisposition, and common allele homozygotes of the two exonic SNPs were more frequent among CD patients than among controls. Concordantly, one out of the three haplotypes carrying both exonic risk alleles was found to increase CD susceptibility (p = 0.007; OR [95%CI] = 1.74 [1.13-2.67]). Therefore, the NOS2A gene seems to be involved in IBD aetiology.

Recent advances in genetic analysis of multiple sclerosis: genetic associations and therapeutic implications

Epidemiological studies have confirmed that genetic factors are a key component in the pathogenesis of multiple sclerosis (MS) and that those determining MS susceptibility have been extensively studied. Many papers have been published regarding the heritable differences useful in genetic studies; these include variations in DNA, such as single-nucleotide polymorphisms, microsatellites and insertion/deletion polymorphisms. However, to date, among other regions, HLA is the only region confirmed to possess genes that determine MS susceptibility. In this article, we review the progress during the last 5 years in the studies on the susceptibility genes and the pharmacogenetics of MS. Newer techniques and methods of analysis will hopefully result in better screening of individuals who are at highest risk and novel treatments.

Confirmation of an Association Between the TNF(−308) Promoter Polymorphism and Stroke Risk in Children With Sickle Cell Anemia

Background and Purpose— The etiology of stroke in children with sickle cell anemia (SCA) is complex and poorly understood. Growing evidence suggests that genetic factors beyond the sickle cell mutation influence stroke risk in SCA. We previously reported risk associations with polymorphisms in several proinflammatory genes in SCA children with ischemic stroke. The aim of this replication study was to confirm our previous findings of associations between the TNF(−308) G/A, IL4R 503 S/P, and ADRB2 27 Q/E polymorphisms and large vessel stroke risk.

Methods— Using previously collected MRA data, we assessed an independent population of SCA children from the multicenter Stroke Prevention Trial in Sickle Cell Anemia (STOP) for the presence or absence of large vessel stenosis. Samples were genotyped for 104 polymorphisms among 65 candidate vascular disease genes. Genotypic associations with risk of large vessel stroke were screened using univariable analysis and compared with results from our original study. Joint analysis of the 2 study populations combined was performed using multivariable logistic regression.

Results— A total of 96 children (49 MRA-positive, 47 MRA-negative) were included in this study. Of the SNP associations previously identified in the original study, the TNF(−308) G/A association with large vessel stroke remained significant and the IL4R 503 S/P variant approached significance in the joint analysis of the combined study populations. Consistent with our original findings, the TNF(−308) GG genotype was associated with a >3-fold increased risk of large vessel disease (OR=3.27; 95% CI=1.6, 6.9; P =0.006). Unadjusted analyses also revealed a previously unidentified association between the LTC4S(−444) A/C variant and large vessel stroke risk.

Conclusions— Similar findings in 2 independent study populations strongly suggest that the TNF(−308) G/A promoter polymorphism is a clinically important risk factor for large vessel stroke in children with SCA. The previously observed association with the IL4R 503 S/P variant and the novel association with the LTC4S(−444) A/C variant suggest that these loci may also contribute to large vessel stroke risk in children with SCA.

Interleukin 7 receptor alpha chain (IL7R) shows allelic and functional association with multiple sclerosis

Multiple sclerosis is a demyelinating neurodegenerative disease with a strong genetic component. Previous genetic risk studies have failed to identify consistently linked regions or genes outside of the major histocompatibility complex on chromosome 6p. We describe allelic association of a polymorphism in the gene encoding the interleukin 7 receptor alpha chain (IL7R) as a significant risk factor for multiple sclerosis in four independent family-based or case-control data sets (overall P = 2.9 x 10(-7)). Further, the likely causal SNP, rs6897932, located within the alternatively spliced exon 6 of IL7R, has a functional effect on gene expression. The SNP influences the amount of soluble and membrane-bound isoforms of the protein by putatively disrupting an exonic splicing silencer.

A follow-up study of Nordic multiple sclerosis candidate gene regions

In this study, the results from three Nordic linkage disequilibrium screens in multiple sclerosis (MS) were investigated, in a new sample set of 314 Nordic MS trios from Denmark, Norway, Sweden and Iceland. Among 30 non-HLA and two HLA microsatellite markers individually genotyped, eight markers displayed distorted transmission with uncorrected P-value <0.05, ranked in this order: D6S2443 (6p21.32, HLA class II) (P corrected =0.01), D2S2201 (2p24), D19S552 (19q13), D3S3584 (3q21), D17S975 (17q11), D1S2627 (1p22), D6S273 (6p21.33, HLA class III) and D12S1051 (12q23). These non-HLA regions need further investigation as possible MS candidate gene regions in our population. Multiple Sclerosis 2007; 13: 584-589. http://msj.sagepub.com

Parental smoking modifies the relation between genetic variation in tumor necrosis factor-alpha (TNF) and childhood asthma

BACKGROUND

Polymorphisms in the proinflammatory cytokine genes tumor necrosis factor-alpha (TNF) and lymphotoxin-alpha (LTA, also called TNF-beta) have been associated with asthma and atopy in some studies. Parental smoking is a consistent risk factor for childhood asthma. Secondhand smoke and ozone both stimulate TNF production.

OBJECTIVES

Our goal was to investigate whether genetic variation in TNF and LTA is associated with asthma and atopy and whether the association is modified by parental smoking in a Mexican population with high ozone exposure.

METHODS

We genotyped six tagging single nucleotide polymorphisms (SNPs) in TNF and LTA, including functional variants, in 596 nuclear families consisting of asthmatics 4-17 years of age and their parents in Mexico City. Atopy was determined by skin prick tests.

RESULTS

The A allele of the TNF-308 SNP was associated with increased risk of asthma [relative risk (RR) = 1.54; 95% confidence interval (CI), 1.04-2.28], especially among children of non-smoking parents (RR = 2.06; 95% CI, 1.19-3.55; p for interaction = 0.09). Similarly, the A allele of the TNF-238 SNP was associated with increased asthma risk among children of nonsmoking parents (RR = 2.21; 95% CI, 1.14-4.30; p for interaction = 0.01). LTA SNPs were not associated with asthma. Haplotype analyses reflected the single SNP findings in magnitude and direction. TNF and LTA SNPs were not associated with the degree of atopy.

CONCLUSIONS

Our results suggest that genetic variation in TNF may contribute to childhood asthma and that associations may be modified by parental smoking.

Association of inducible nitric oxide synthase with asthma severity, total serum immunoglobulin E and blood eosinophil levels

BACKGROUND

Nitric oxide is released by immune, epithelial and endothelial cells, and plays an important part in the pathophysiology of asthma.

OBJECTIVE

To investigate the association of inducible nitric oxide synthases (iNOS) gene repeat polymorphisms with asthma.

METHODS

230 families with asthma (842 individuals) were recruited to identify and establish the genetic association of iNOS repeats with asthma and associated phenotypes. Serum nitric oxide levels in selected individuals were measured and correlated with specific genotypes. Multiple logistic regression analysis was performed to determine the effect of age and sex.

RESULTS

A total of four repeats-a (CCTTT)n promoter repeat, a novel intron 2 (GT)n repeat (BV680047), an intron 4 (GT)n repeat (AFM311ZB1) and an intron 5 (CA)n repeat (D17S1878)-were identified and genotyped. A significant transmission distortion to the probands with asthma was seen for allele 3 of the AFM311ZB1 gene (p = 0.006). This allele was also found to be significantly associated with percentage blood eosinophils (p < 0.001) and asthma severity (p = 0.04). Moreover, it was functionally correlated with high serum nitric oxide levels (p = 0.006). Similarly, the promoter repeat was found to be associated with serum total immunoglobulin (Ig)E (p = 0.028). Individuals carrying allele 4 of this repeat have high serum IgE (p < 0.001) and nitric oxide levels (p = 0.03).

CONCLUSION

This is the first study to identify the repeat polymorphisms in the iNOS gene that are associated with severity of asthma and eosinophils. The functional relevance of the associated alleles with serum nitric oxide levels was also shown. Therefore, these results could be valuable in elucidating the role of nitric oxide in asthma pathogenesis.

Variants of chemokine receptor 2 and interleukin 4 receptor, but not interleukin 10 or Fas ligand, increase risk of cervical cancer

Cervical cancer is caused by persistent infection of oncogenic human papillomavirus (HPV). Most infected women clear the virus without developing cervical lesions and it is likely that immunological host factors affect susceptibility to cervical cancer. The impact of the human leukocyte antigen (HLA) locus on the risk of cervical cancer is established and several other genes involved in immunological pathways have been suggested as biologically plausible candidates. The aim of this study was to examine the potential role of polymorphisms in 4 candidate genes by analysis of 1,306 familial cervical cancer cases and 288 controls. The following genes and polymorphisms were studied: Chemokine receptor 2 (CCR-2) V64I; Interleukin 4 receptor alpha (IL-4R) I75V, S503P and Q576R; Interleukin 10 (IL-10) -592; and Fas ligand (FasL) -844. The CCR-2 64I variant was associated with decreased risk of cervical cancer; homozygote carriers of the 64I variant had an odds ratio of 0.31 (0.12-0.77). This association was detected in both carriers and noncarriers of the HLA DQB1*0602 cervical cancer risk allele. The IL-4R 75V variant was associated with increased risk of cervical tumors, cases homozygote for 75V had an odds ratio of 1.91 (1.27-2.86) with a tendency that the association was stronger in noncarriers of the DQB1*0602 allele. We did not find any association for IL-10 -592, or FasL -844, previously reported to be associated with cervical cancer in the Dutch and Chinese populations, respectively.

Linkage disequilibrium with predisposing DR3 haplotypes accounts for apparent effects of tumor necrosis factor and lymphotoxin-alpha polymorphisms on type 1 diabetes susceptibility

Tumor necrosis factor (TNF) and lymphotoxin alpha (LT-alpha) are immunomodulators that have been hypothesized to contribute to susceptibility to type 1 diabetes (T1D). Several polymorphisms in the TNF and LT-alpha loci have been extensively studied for T1D association, with conflicting reports. In this study, we examined two TNF variants and one LT-alpha variant for T1D association in 283 Caucasian, multiplex T1D families for which complete human leukocyte antigen (HLA) genotyping data are available. Initially, association with T1D was seen for LT-alpha A1069G (intron A, p=0.011, rs909253) and TNF G(-308)A (p<1x10(-5), rs1800629), but no association was observed for TNF G(-238)A (rs361525). After adjusting the data for linkage disequilibrium (LD) with DRB1-DQB1 haplotypes, however, only one polymorphism, TNF G(-238)A showed significant association with T1D (p<0.006). When HLA-DR3 haplotypes were examined, the A allele of TNF G(-238)A was significantly overtransmitted to affected offspring (p<0.009). Including HLA-B data in the analysis revealed that TNF (-238)A is present exclusively on DR3 haplotypes that also carry HLA-B18. Transmission proportion of B18-DR3 haplotypes did not differ between those with TNF (-238)A and those with TNF (-238)G. Thus, variation at TNF does not affect the T1D risk for B18-DR3 haplotypes, and the apparent association of TNF(-238)A with T1D may simply reflect its presence on a high-risk haplotype.

Complex gene-gene interactions in multiple sclerosis: a multifactorial approach reveals associations with inflammatory genes

The complex inheritance involved in multiple sclerosis (MS) risk has been extensively investigated, but our understanding of MS genetics remains rudimentary. In this study, we explore 51 single nucleotide polymorphisms (SNPs) in 36 candidate genes from the inflammatory pathway and test for gene-gene interactions using complementary case-control, discordant sibling pair, and trio family study designs. We used a sample of 421 carefully diagnosed MS cases and 96 unrelated, healthy controls; discordant sibling pairs from 146 multiplex families; and 275 trio families. We used multifactor dimensionality reduction to explore gene-gene interactions. Based on our analyses, we have identified several statistically significant models including both main effect models and two-locus, three-locus, and four-locus epistasis models that predict MS disease risk with between approximately 61% and 85% accuracy. These results suggest that significant epistasis, or gene-gene interactions, may exist even in the absence of statistically significant individual main effects.

Inducible and endothelial nitric oxide synthase genes polymorphism in inflammatory bowel disease

To assess the influence of inducible and endothelial nitric oxide synthase gene (NOS2A and NOS3) polymorphisms in susceptibility to Crohn's disease (CD) and ulcerative colitis (UC). A total of 505 inflammatory bowel disease (IBD) patients (221 with UC and 284 with CD) and 332 ethnically matched controls were studied. Patients and controls were genotyped by polymerase chain reaction -based techniques for a multiallelic (CCTTT)(n) repeat and biallelic marker (TAAA)(n) in the promoter region of the NOS2A gene and for a T/C polymorphism at position -786 in the promoter region and a polymorphism in exon 7(298Glu/Asp) of the NOS3 gene. There was not association between NOS2A and NOS3 genotypes, alleles or haplotypes frequencies with UC, CD and controls. Our data suggest that NOS2A and NOS3 polymorphisms do not play a major role in IBD predisposition.

Allelic association of sequence variants in the herpes virus entry mediator-B gene (PVRL2) with the severity of multiple sclerosis

Discrepant findings have been reported regarding an association of the apolipoprotein E (APOE) gene with the clinical course of multiple sclerosis (MS). To resolve these discrepancies, we examined common sequence variation in six candidate genes residing in a 380-kb genomic region surrounding and including the APOE locus for an association with MS severity. We genotyped at least three polymorphisms in each of six candidate genes in 1,540 Caucasian MS families (729 single-case and multiple-case families from the United States, 811 single-case families from the UK). By applying the quantitative transmission/disequilibrium test to a recently proposed MS severity score, the only statistically significant (P=0.003) association with MS severity was found for an intronic variant in the Herpes Virus Entry Mediator-B Gene PVRL2. Additional genotyping extended the association to a 16.6 kb block spanning intron 1 to intron 2 of the gene. Sequencing of PVRL2 failed to identify variants with an obvious functional role. In conclusion, the analysis of a very large data set suggests that genetic polymorphisms in PVRL2 may influence MS severity and supports the possibility that viral factors may contribute to the clinical course of MS, consistent with previous reports.

Genetic inflammatory factors predict restenosis after percutaneous coronary interventions

BACKGROUND

Restenosis is a negative effect of percutaneous coronary intervention (PCI). No clinical factors are available that allow good risk stratification. However, evidence exists that genetic factors are important in the restenotic process as well as in the process of inflammation, a pivotal factor in restenosis. Association studies have identified genes that may predispose to restenosis, but confirmation by large prospective studies is lacking. Our aim was to identify polymorphisms and haplotypes in genes involved in inflammatory pathways that predispose to restenosis.

METHODS AND RESULTS

The GENetic DEterminants of Restenosis (GENDER) project is a multicenter prospective study, including 3104 consecutive patients after successful PCI. Forty-eight polymorphisms in 34 genes in pathways possibly involved in the inflammatory process were analyzed. The 16Gly variant of the beta2-adrenergic receptor gave an increased risk of target vessel revascularization (TVR). The rare alleles of the CD14 gene (-260T/T), colony-stimulating factor 2 gene (117Thr/Thr), and eotaxin gene (-1328A/A) were associated with decreased risk of TVR. However, through the use of multiple testing corrections with permutation analysis, the probability of finding 4 significant markers by chance was 12%.

CONCLUSIONS

Polymorphisms in 4 genes considered involved in the inflammatory reaction showed an association with TVR after PCI. Our results may contribute to the unraveling of the restenotic process. Given the explorative nature of this analysis, our results need to be replicated in other studies.

Tumor necrosis factor-alpha plays an important role in restenosis development

Genetic factors appear to be important in the restenotic process after percutaneous coronary intervention (PCI), as well as in inflammation, a pivotal factor in restenosis. TNFalpha, a key regulator of inflammatory responses, may exert critical influence on the development of restenosis after PCI. The GENetic DEterminants of Restenosis (GENDER) project included 3104 patients who underwent a successful PCI. Systematic genotyping for six polymorphisms in the TNFalpha gene was performed. The role of TNFalpha in restenosis was also assessed in ApoE*3-Leiden mice, TNFalpha knockout mice, and by local delivery of a TNFalpha biosynthesis inhibitor, thalidomide. The -238G-1031T haplotype of the TNFalpha gene increased clinical and angiographic risk of restenosis (P=0.02 and P=0.002, respectively). In a mouse model of reactive stenosis, arterial TNFalpha mRNA was significantly time-dependently up-regulated. Mice lacking TNFalpha or treated locally with thalidomide showed a reduction in reactive stenosis (P=0.01 and P=0.005, respectively). Clinical and preclinical data indicate that TNFalpha plays an important role in restenosis. Therefore, TNFalpha genotype may be used as a risk marker for restenosis and may contribute to individual patient screening prior to PCI in clinical practice. Inhibition of TNFalpha may be an anti-restenotic target strategy.

Lipoprotein lipase gene polymorphisms and the risk of target vessel revascularization after percutaneous coronary intervention

OBJECTIVES

We sought to identify polymorphisms in genes that predispose to restenosis.

BACKGROUND

Variations in the lipoprotein lipase (LPL) gene have been implicated in a number of pathophysiologic conditions associated with coronary heart disease. The present study examines the impact of polymorphisms in the LPL gene on restenosis (defined by target vessel revascularization [TVR]) in a large patient population undergoing percutaneous coronary intervention (PCI). A mouse model for restenosis was used to further investigate LPL's role in restenosis.

METHODS

The GENetic DEterminants of Restenosis (GENDER) project is a multicenter, prospective study design that enrolled 3,104 consecutive patients after successful PCI. These patients were genotyped for four different LPL gene polymorphisms. In apolipoprotein E (ApoE)*3-Leiden transgenic mice, arterial messenger ribonucleic acid (mRNA) was used to assess LPL expression during a cuff-induced restenotic process.

RESULTS

Using multivariable analysis, carriers of the 447Ter allele of the LPL enzyme showed a lower risk of TVR compared with 447Ser homozygotes (p = 0.005). In the mouse model, LPL mRNA levels were increased 40-fold compared with control arteries at 6 h after cuff placement.

CONCLUSIONS

The LPL C/G polymorphism (Ser447Ter), resulting in a truncation of the two C-terminal amino acids of the mature LPL protein, appears to be an important protective factor for TVR in humans. The role of LPL in this process was further established in a mouse model, where LPL expression was very strongly up-regulated in the target arterial wall, suggesting a contribution of this lipolytic enzyme to restenosis. Possibly, LPL Ser447Ter genotyping may lead to better risk stratification and tailored therapy in the prevention of restenosis after PCI.

Multiple sclerosis genetics: leaving no stone unturned

Compelling epidemiologic and molecular data indicate that genes play a primary role in determining who is at risk for developing multiple sclerosis (MS), how the disease progresses, and how someone responds to therapy. The genetic component of MS etiology is believed to result from the action of allelic variants in several genes. Their incomplete penetrance and moderate individual effect probably reflects epistatic interactions, post-transcriptional regulatory mechanisms, and significant environmental influences. Equally significant, it is also likely that locus heterogeneity exists, whereby specific genes influence susceptibility and pathogenesis in some individuals but not in others. With the aid of novel analytical algorithms, the combined study of genomic, transcriptional, proteomic, and phenotypic information in well-controlled study groups will define a useful conceptual model of pathogenesis and a framework for understanding the mechanisms of action of existing therapies for this disorder, as well as the rationale for novel curative strategies.

Nitric oxide and multiple sclerosis

Nitric oxide (NO) is a free radical signaling molecule with remarkably complex biochemistry. Its involvement in multiple sclerosis (MS) had been postulated soon after the discovery of the critical role NO plays in inflammation. However, the extent of NO's contribution to MS is not yet understood, party due to the often opposing roles that NO can play in cellular processes. This review briefly covers new developments in the area of NO that may be relevant to MS. It also describes recent progress in understanding the role of NO in MS, new potential targets of the action of NO in the cell, and prospects for NO-based therapies.

An investigation of NOS2A promoter polymorphisms in Australian multiple sclerosis patients

As with other major autoimmune diseases, susceptibility to multiple sclerosis (MS) is believed to result from the complex interaction of a number of genes, each with modest effect. Extensive research of experimental autoimmune encephalomyelitis in mice and several direct MS studies have implicated NOS2A, which encodes the inducible form of nitric oxide synthase, and the genetic region encoding NOS2A, 17q11.2, has been identified in a number of genome wide screens as being potentially associated with MS. We investigated four single nucleotide polymorphisms in the proximal promoter region of NOS2A, in a case-control group of 100 Australian MS patients and 100 controls and in 203 MS patients and their unaffected parents. We found a trend toward excess transmission of the -277A allele (tag for the AGCC haplotype) to HLA-DRB1*1501-positive MS patients (P (uncorrected)=0.05). We initially discovered a trend toward over-representation of the AGCC haplotype in HLA-DRB1*1501-positive compared to HLA-DRB1*1501-negative MS patients in the case-control cohort. However, when combined with the probands from the transmission disequilibrium analysis, this trend was nullified. Nonetheless, despite the lack of significant evidence of association for the NOS2A promoter polymorphisms with MS, the gene remains an interesting candidate for MS susceptibility, particularly with regard to the HLA-DRB1*1501 haplotype.

Haplotypes within genes of beta-chemokines in 17q11 are associated with multiple sclerosis: a second phase study

We previously defined haplotypes of single nucleotide polymorphisms (SNP) with possible relevance to multiple sclerosis (MS) in 2 CC chemokine ligand (CCL) clusters in chromosome 17q11. The 17q11 region was also identified as a susceptibility locus by a meta-analysis of linkage studies. To confirm and refine the previous finding in a second, high resolution SNP scan in a new set of families. We genotyped 232 SNPs in 1369 individuals in 361 MS families. Transmission of marker alleles and haplotypes from unaffected parents to affected offspring was tested by using the pedigree disequilibrium test, the TRANSMIT 2.5 program, and the family and haplotype based association tests. Distribution of linkage disequilibrium (LD) was assessed by ldmax. In consensus with observations in the first scan, the present study identified haplotypes within CCL3 and CCL15 in the telomeric CCL cluster. There was also an overlap in the findings in the centromeric CCL cluster. Strong and extensive LD was detected both within the centromeric and telomeric CCL gene clusters. The present study replicates our previous findings and further suggests the existence of MS associated haplotypes within genes of CCL3 and CCL15. Haplotypes of interest are also present within the centromeric gene cluster (including CCL2, CCL7, CCL11, CCL8, and CCL13), but extensive LD prevents further refinement of these haplotypes by using the methods applied. Sequencing of the identified chromosomal segments and their flanking regions will be necessary to define specific variants with direct relevance to MS pathogenesis.

Pathogenesis of multiple sclerosis

PURPOSE OF REVIEW

The aim of this article is to describe recent observations regarding the basis for the initiation and disease evolution of multiple sclerosis.

RECENT FINDINGS

A current debate is where and what initiates the neuroinflammatory reaction that characterizes the acute multiple sclerosis lesion. Immune sensitization to neural antigens could develop within the systemic compartment consequent to exposure to cross-reacting, possibly viral derived, peptides (molecular mimicry). Although CD4 T cells are considered central to initiating central nervous system inflammation, the actual extent and specificity of tissue injury reflects the array of adaptive (CD8 T cells and antibody) and innate (microglia/macrophages) immune constituents present in the lesions. Neuropathologic studies indicate that lethal changes in neural cells (oligodendrocytes) could also be the initiating event, reflecting as yet unidentified acquired insults (e.g. exogenous virus or reactivated endogenous retrovirus) or intrinsic abnormalities ('neurodegenerative' hypothesis). Recurrence or persistence of the disease process can reflect events occurring at multiple sites including expansion of the immune repertoire in response to neural antigens transported to regional lymph nodes (determinant spreading), especially if immune regulatory mechanisms are defective; alterations in blood-brain barrier properties consequent to initial cellular transmigration; and participation of endogenous (microglia, astrocytes) or long lived infiltrating cells (macrophages, B cells in ectopic germinal centers) in regulating and effecting immune functions within the central nervous system. Accumulating neurologic deficit reflects the balance between injury and repair; the latter also being negatively or positively (trophic support and clearance of tissue debris) impacted by inflammatory processes.

SUMMARY

Understanding the full spectrum of multiple sclerosis presents a continuing challenge for both immunology and neurobiology.

Genomics, proteomics, metabolomics: what is in a word for multiple sclerosis?

PURPOSE OF REVIEW

Multiple sclerosis (MS) is the most common chronic inflammatory neurological disease. Despite major advances the aetiology of this disease it is still not completely understood. In the post-genome era, advances in global screening technologies offer an opportunity to accelerate the search of new pathological pathways and to identify new therapeutic targets. Some recent publications using novel global screening methods at the genome, transcriptome, proteome and metabolome levels are discussed.

RECENT FINDINGS

The genetic association of susceptibility to MS with loci outside the MHC has been reconfirmed. Evidence of parent-of-origin and seasonal effects on disease susceptibility add further complexity to the genetics of MS. The search for MS susceptibility genes continues using the candidate-gene approach as well as large-scale single-nucleotide-polymorphism association studies and novel cross-species synteny analysis. Genome-wide expression profiling using microarrays produced numerous therapeutic targets and is progressing towards profiling of rare cells. Advances in classical proteomics methods paved the way to new initiatives aiming at determining the proteome of the nervous system in normal and diseased states. Although progress is still slow, array-based methods are making an impact on the MS field.

SUMMARY

The complexity of MS is clearly reflected in the latest findings using global profiling methods. Nevertheless, these new technologies are confirming some of the basic aspects of the disease pathophysiology, i.e. its polygenicity, the central role of neuroinflammation and the emerging neurodegenerative processes. These data are primarily the results of genomic approaches, yet promising attempts are also made using proteomics and metabolomics.

Investigation of an inducible nitric oxide synthase gene (NOS2A) polymorphism in a multiple sclerosis population

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) affecting most commonly the Caucasian population. Nitric oxide (NO) is a biological signaling and effector molecule and is especially important during inflammation. Inducible nitric oxide synthase (iNOS) is one of the three enzymes responsible for generating NO. It has been reported that there is an excessive production of NO in MS concordant with an increased expression of iNOS in MS lesions. This study investigated the role of a bi-allelic tetranucleotide polymorphism located in the promoter region of the human iNOS (NOS2A) gene in MS susceptibility. A group of MS patients (n = 101) were genotyped and compared to an age- and sex-matched group of healthy controls (n = 101). The MS group was subdivided into three subtypes, namely relapsing-remitting MS (RR-MS), secondary-progressive MS (SP-MS) and primary-progressive MS (PP-MS). Results of a chi-squared analysis and a Fisher's exact test revealed that allele and genotype distributions between cases and controls were not significantly different for the total population (chi(2) = 3.4, P(genotype) = 0.15; chi(2) = 3.4, P(allele) = 0.082) and for each subtype of MS (P > 0.05). This suggests that there is no direct association of this iNOS gene variant with MS susceptibility.