TTC7B emerges as a novel risk factor for ischemic stroke through the convergence of several genome-wide approaches.

We hereby propose a novel approach to the identification of ischemic stroke (IS) susceptibility genes that involves converging data from several unbiased genetic and genomic tools. We tested the association between IS and genes differentially expressed between cases and controls, then determined which data mapped to previously reported linkage peaks and were nominally associated with stroke in published genome-wide association studies. We first performed gene expression profiling in peripheral blood mononuclear cells of 20 IS cases and 20 controls. Sixteen differentially expressed genes mapped to reported whole-genome linkage peaks, including the TTC7B gene, which has been associated with major cardiovascular disease. At the TTC7B locus, 46 tagging polymorphisms were tested for association in 565 Portuguese IS cases and 520 controls. Markers nominally associated in at least one test and defining associated haplotypes were then examined in 570 IS Spanish cases and 390 controls. Several polymorphisms and haplotypes in the intron 5-intron 6 region of TTC7B were also associated with IS risk in the Spanish and combined data sets. Multiple independent lines of evidence therefore support the role of TTC7B in stroke susceptibility, but further work is warranted to identify the exact risk variant and its pathogenic potential.

Replication of the CELSR1 association with ischemic stroke in a Portuguese case-control cohort.

OBJECTIVES: Replication of GWAS association findings remains the gold standard for results validation. Our aim was to test the association of four polymorphisms (rs1671021 in LLGL2, rs753307 in RUVBL2, rs6007897 and rs4044210 in CELSR1) previously identified as ischemic stroke (IS) risk factors in a phased GWAS performed on 6341 Japanese individuals [1]. METHODS: These polymorphisms were genotyped in a Portuguese sample of 566 IS cases and 525 controls, and their allele, genotype and haplotype associations were assessed. RESULTS: rs6007897 and rs4044210 in CELSR1 were associated with stroke risk individually (OR[95%CI]=1.43[1.13-1.81], p=0.003 and 1.38[1.09-1.74], p=0.007, respectively), and in combination as a haplotype. These associations remain after correction for multiple testing and in a meta-analysis with the original findings. The other polymorphisms were not associated. CONCLUSIONS: Our study independently confirmed for the first time the association between IS and CELSR1. This finding and the mechanisms by which these genetic variants exert their effects on stroke pathogenesis warrant further replication and investigation.

Association of a genetic variant in the ALOX5AP with higher risk of ischemic stroke: a case-control, meta-analysis and functional study.

BACKGROUND: Variants in the 5-lipoxygenase-activating protein (ALOX5AP) and phosphodiesterase 4D (PDE4D) genes have first been associated with ischemic stroke (IS) through whole-genome linkage screens. However, association studies obtained conflicting results. We aimed to investigate the contribution of selected single nucleotide polymorphisms (SNPs) in these genes for the first time in a large Iberian population. METHODS: A case-control design was used to analyze one SNP in ALOX5AP and five SNPs in PDE4D in a total of 1,092 IS patients and 781 healthy controls of two different subsets from Spain and Portugal. The analysis was adjusted for confounding variables and the results were integrated in a meta-analysis of all case-control studies. In addition, ALOX5AP gene expression levels were determined in controls and IS cases. RESULTS: A first meta-analysis of both subsets showed that the T allele of the SG13S114 SNP in ALOX5AP was a risk factor for IS after Bonferroni correction [OR = 1.22 (1.06-1.40); p = 0.006]. A second meta-analysis of white populations confirmed these results [OR = 1.18 (1.07-1.31); p = 0.001]. ALOX5AP gene expression analysis in a subset of controls and cases revealed that the SG13S114 genotypes modulate mRNA levels of ALOX5AP (p = 0.001) and mRNA levels were higher in IS cases (2.8 +/- 2.4%) than in controls (1.4 +/- 1.3%; p = 0.003). No association of the variants in PDE4D with IS was observed in our study. CONCLUSIONS: The ALOX5AP SG13S114 variant is an independent risk factor for IS in the Iberian population and is associated with ALOX5AP expression levels. The role of this gene in stroke merits further investigation.

Kalirin: a novel genetic risk factor for ischemic stroke.

Cerebrovascular and cardiovascular diseases are the leading causes of death and disability worldwide. They are complex disorders resulting from the interplay of genetic and environmental factors, and may share several susceptibility genes. Several recent studies have implicated variants of the Kalirin (KALRN) gene with susceptibility to cardiovascular and metabolic phenotypes, but no studies have yet been performed in stroke patients. KALRN is involved, among others, in the inhibition of inducible nitric oxide synthase, in the regulation of ischemic signal transduction, and in neuronal morphogenesis, plasticity, and stability. The goal of the present study was to determine whether SNPs in the KALRN region on 3q13, which includes the Ropporin gene (ROPN1), predispose to ischemic stroke (IS) in a cohort of Portuguese patients and controls. We genotyped 34 tagging SNPs in the KALRN and ROPN1 chromosomal region on 565 IS patients and 517 unrelated controls, and performed genotype imputation for 405 markers on chromosome 3. We tested the single-marker association of these SNPs with IS. One SNP (rs4499545) in the ROPN1-KALRN intergenic region and two SNPs in KALRN (rs17286604 and rs11712619) showed significant (P < 0.05) allelic and genotypic (unadjusted and adjusted for hypertension, diabetes, and ever smoking) association with IS risk. Thirty-two imputed SNPs also showed an association at P < 0.05, and actual genotyping of three of these polymorphisms (rs7620580, rs6438833, and rs11712039) validated their association. Furthermore, rs11712039 was associated with IS (0.001 < P < 0.01) in a recent well-powered genomewide association study (Ikram et al. 2009). These studies suggest that variants in the KALRN gene region constitute risk factors for stroke and that KALRN may represent a common risk factor for vascular diseases.

MTHFR and the risk for cerebral venous thrombosis--a meta-analysis.

BACKGROUND: The association between methylenotetrahydrofolate reductase (MTHFR) 677TT and the increased risk of venous thrombosis is uncertain. Studies of this polymorphism in cerebral venous thrombosis (CVT) are inconclusive. OBJECTIVES: With a systematic review, we aimed to collect all case-control studies comparing the frequency of this polymorphism in CVT patients (cases) and healthy controls. METHODS: We used the MEDLINE, Cochrane Library and the ISI web of knowledge electronic databases and reference lists of retrieved articles in order to identify published case-control studies that evaluated the presence of MTHFR 677C>T polymorphism in CVT. Two reviewers independently selected studies. We compared the frequency of 677TT between cases and controls using the Mantel-Haenszel method, a fixed and a random-effects model in the pooled data. RESULTS: Nine case-control studies were included. The pooled analysis included 382 patients with CVT and 1217 controls. The frequency of 677TT genotype among CVT patients was not significantly higher compared with controls (15.7% versus 14.6%; OR=1.12, 95% confidence interval (95% CI) 0.80 to 1.58; p=0.50). There was significant heterogeneity between studies. CONCLUSIONS: This meta-analysis confirmed that there is currently insufficient data supporting that 677TT genotype is a risk factor for CVT. These results imply a continuing searching for the cause of CVT in patients with this polymorphism.

Safety of chiropractic interventions: a systematic review.

STUDY DESIGN: Systematic review of reported adverse events. OBJECTIVE: To evaluate the tolerability and safety of chiropractic procedures. SUMMARY OF BACKGROUND DATA: Despite the increasing popularity of chiropractic, there are few properly designed prospective controlled trials, and there is a disproportionate lack of evaluation of its safety profile. The literature reports multiple neurologic complications of spinal manipulation, some of which are clinically relevant and even life threatening. METHODS: We performed an electronic search in 2 databases: Pubmed and the Cochrane Library for the years 1966 to 2007. All articles that reported adverse reactions associated with chiropractic were included irrespective of type of design. The outcome measures were the type of adverse events associated or attributed to chiropractic interventions and their frequency. RESULTS: A total of 376 potential relevant articles were identified, 330 of which were discarded after abstract or complete article analysis. The search identified 46 articles that included data concerning adverse events: 1 randomized controlled trial, 2 case-control studies, 7 prospective studies, 12 surveys, 3 retrospective studies, and 115 case reports. Most of the adverse events reported were benign and transitory, however, there are reports of complications that were life threatening, such as arterial dissection, myelopathy, vertebral disc extrusion, and epidural hematoma. The frequency of adverse events varied between 33% and 60.9%, and the frequency of serious adverse events varied between 5 strokes/100,000 manipulations to 1.46 serious adverse events/10,000,000 manipulations and 2.68 deaths/10,000,000 manipulations. CONCLUSION: There is no robust data concerning the incidence or prevalence of adverse reactions after chiropractic. Further investigations are urgently needed to assess definite conclusions regarding this issue.

Mitochondrial haplogroup H1 is protective for ischemic stroke in Portuguese patients.

BACKGROUND: The genetic contribution to stroke is well established but it has proven difficult to identify the genes and the disease-associated alleles mediating this effect, possibly because only nuclear genes have been intensely investigated so far. Mitochondrial DNA (mtDNA) has been implicated in several disorders having stroke as one of its clinical manifestations. The aim of this case-control study was to assess the contribution of mtDNA polymorphisms and haplogroups to ischemic stroke risk. METHODS: We genotyped 19 mtDNA single nucleotide polymorphisms (SNPs) defining the major European haplogroups in 534 ischemic stroke patients and 499 controls collected in Portugal, and tested their allelic and haplogroup association with ischemic stroke risk. RESULTS: Haplogroup H1 was found to be significantly less frequent in stroke patients than in controls (OR = 0.61, 95% CI = 0.45-0.83, p = 0.001), when comparing each clade against all other haplogroups pooled together. Conversely, the pre-HV/HV and U mtDNA lineages emerge as potential genetic factors conferring risk for stroke (OR = 3.14, 95% CI = 1.41-7.01, p = 0.003, and OR = 2.87, 95% CI = 1.13-7.28, p = 0.021, respectively). SNPs m.3010G>A, m.7028C>T and m.11719G>A strongly influence ischemic stroke risk, their allelic state in haplogroup H1 corroborating its protective effect. CONCLUSION: Our data suggests that mitochondrial haplogroup H1 has an impact on ischemic stroke risk in a Portuguese sample.

Chiropractic manipulation: reasons for concern?

Chiropractic's popularity is rising among the general population. Moreover, few studies have been conducted to properly evaluate its safety. We report three cases of serious neurological adverse events in patients treated with chiropractic manipulation. The first case is a 41 years old woman who developed a vertebro-basilar stroke 48 h after cervical manipulation. The second case represents a 68 years old woman who presented a neuropraxic injury of both radial nerves after three sessions of spinal manipulation. The last case is a 34 years old man who developed a cervical epidural haematoma after a chiropractic treatment for neck pain. In all three cases there were criteria to consider a causality relation between the neurological adverse events and the chiropractic manipulation. The described serious adverse events promptly recommend the implementation of a risk alert system.

Young-onset sporadic amyotrophic lateral sclerosis: a distinct nosological entity?

There are few reports describing young-onset amyotrophic lateral sclerosis (ALS). Age at onset is a prognostic factor in ALS, and thus it is relevant to investigate the clinical features of very young ALS patients. We describe three young-onset ALS cases and review the literature. SOD1 mutations were not identified. Our cases and 24 others from the literature indicate that young-onset ALS is characterized by slowly progressive symmetrical weakness; nevertheless, progression is variable. Young-onset ALS seems to be a distinct clinical syndrome but its aetiological background is largely unknown.