Polymorphisms in chromosome 9 and risk of ischemic stroke in two European white populations, and a meta-analysis

Genetic determinants of juvenile stroke

Stroke is a heterogeneous multifactorial disorder. Although epidemiological data from twin and family studies provide substantial evidence for a genetic basis for stroke, the contribution of genetic factors identified so far is small. Large progress has been made in single-gene disorders associated with ischemic stroke, particularly at young age. The identification of NOTCH3 mutations in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) and of TREX1 mutations in retinal vasculopathy with cerebral leukodystrophy (RVCL) have led to new insights on lacunar stroke and small-vessel disease. Studies of sickle-cell disease have drawn attention to the importance of modifier genes and of gene-gene interactions in determining stroke risk, while there is now evidence that Fabry disease is an underdiagnosed cause of stroke. Furthermore, stroke is a well-known complication of several heritable connective tissue disorders, including Marfan's syndrome (FBN1 mutations) and Ehlers-Danlos syndrome type IV (COL3A1 mutations), which predispose to cervical artery dissection, the most frequent cause of cerebral ischemia at young age. By contrast, little is known about the genes associated with multifactorial stroke. The reported genome-wide association studies of ischemic stroke have shown that no single common genetic variant imparts major risk. Pharmacogenomic studies have uncovered genetic determinants of response to warfarin, statins and clopidogrel. Larger studies with samples numbering in the thousands are ongoing to identify common variants with smaller effects on risk. This approach will contribute to the identification of additional genes, novel pathways, and eventually novel therapeutic approaches to cerebrovascular disorders.

Tissue factor gene polymorphisms and haplotypes and the risk of ischemic vascular events: four studies and a meta-analysis

OBJECTIVE

The exposure of tissue factor (TF) to blood flow is the initial step in the coagulation process and plays an important role in thrombogenesis. We investigated the role of genetic polymorphisms and haplotypes of the TF gene in the risk of ischemic vascular disease.

METHODS

Four hundred and twenty-two Italian patients with juvenile myocardial infarction (MI) and 434 controls, 808 US cases with MI and 1005 controls, 267 Italian cases with juvenile ischemic stroke and 209 controls and 148 German cases with juvenile ischemic stroke and 191 controls were studied. rs1361600, rs3917629 (rs3354 in the US population), rs1324214 and rs3917639 Tag single nucleotide polymorphisms were genotyped. Additionally, a meta-analysis of all previous studies on TF loci and the risk of ischemic coronary disease (ICD) was performed.

RESULTS

After multivariable analysis none of the SNPs, major SNP haplotypes or haplotype-pairs showed any consistent association with MI. Pooled meta-analysis of six studies also suggested that TF polymorphisms are not associated with CHD. A significant, independent association between SNP rs1324214 (C/T) and juvenile stroke was found in Italian and German populations (OR for TT homozygotes = 0.47, 95% CI 0.24-0.92, in combined analysis). Pooled analysis also showed a significant association for haplotype H3 (OR = 0.76, 95% CI 0.57-1.00) and haplotype-pair H3-H3 (OR = 0.43, 95% CI 0.20-0.92).

CONCLUSIONS

TF genetic variations were associated with the risk of ischemic stroke at young age, but did not affect ischemic coronary disease.