Meta-analysis of type 2 Diabetes in African Americans Consortium

Type 2 diabetes (T2D) is more prevalent in African Americans than in Europeans. However, little is known about the genetic risk in African Americans despite the recent identification of more than 70 T2D loci primarily by genome-wide association studies (GWAS) in individuals of European ancestry. In order to investigate the genetic architecture of T2D in African Americans, the MEta-analysis of type 2 DIabetes in African Americans (MEDIA) Consortium examined 17 GWAS on T2D comprising 8,284 cases and 15,543 controls in African Americans in stage 1 analysis. Single nucleotide polymorphisms (SNPs) association analysis was conducted in each study under the additive model after adjustment for age, sex, study site, and principal components. Meta-analysis of approximately 2.6 million genotyped and imputed SNPs in all studies was conducted using an inverse variance-weighted fixed effect model. Replications were performed to follow up 21 loci in up to 6,061 cases and 5,483 controls in African Americans, and 8,130 cases and 38,987 controls of European ancestry. We identified three known loci (TCF7L2, HMGA2 and KCNQ1) and two novel loci (HLA-B and INS-IGF2) at genome-wide significance (4.15 × 10(-94)<P<5 × 10(-8), odds ratio (OR)  = 1.09 to 1.36). Fine-mapping revealed that 88 of 158 previously identified T2D or glucose homeostasis loci demonstrated nominal to highly significant association (2.2 × 10(-23) < locus-wide P<0.05). These novel and previously identified loci yielded a sibling relative risk of 1.19, explaining 17.5% of the phenotypic variance of T2D on the liability scale in African Americans. Overall, this study identified two novel susceptibility loci for T2D in African Americans. A substantial number of previously reported loci are transferable to African Americans after accounting for linkage disequilibrium, enabling fine mapping of causal variants in trans-ethnic meta-analysis studies.Peer reviewe

Migraine in cervical artery dissection and ischemic stroke patients: the CADISP Study.

Objective: Several small to medium-sized studies indicated a link between cervical artery dissection (CeAD) and migraine. Migrainous CeAD patients were suggested to have different clinical characteristics compared to nonmigraine CeAD patients. We tested these hypotheses in the large Cervical Artery Dissection and Ischemic Stroke Patients (CADISP) population. Methods: A total of 968 CeAD patients and 653 patients with an ischemic stroke of a cause other than CeAD (non-CeAD IS) were recruited. CeAD patients with stroke (CeADstroke, n = 635) were compared with non-CeAD IS patients regarding migraine, clinical characteristics, and outcome. CeAD patients with and without migraine were compared in terms of clinical characteristics and outcome. Results: Migraine was more common among CeAD stroke patients compared to non-CeAD IS patients (35.7 vs 27.4%, p = 0.003). The difference was mainly due to migraine without aura (20.2 vs 11.2%, p<0.001). There were no differences in prevalence of strokes, arterial distribution, or other clinical or prognostic features between migrainous and nonmigrainous CeAD patients. Conclusion: Migraine without aura is more common among CeADstroke patients compared to non- CeAD IS patients. The mechanisms and possible causative link remain to be proved. Although CeAD is often complicated by stroke, our data do not support increased risk of stroke in migrainous CeAD patients. Copyright © 2012 by AAN Enterprises, Inc.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Common variation in PHACTR1 is associated with susceptibility to cervical artery dissection.

Cervical artery dissection (CeAD), a mural hematoma in a carotid or vertebral artery, is a major cause of ischemic stroke in young adults although relatively uncommon in the general population (incidence of 2.6/100,000 per year). Minor cervical traumas, infection, migraine and hypertension are putative risk factors, and inverse associations with obesity and hypercholesterolemia are described. No confirmed genetic susceptibility factors have been identified using candidate gene approaches. We performed genome-wide association studies (GWAS) in 1,393 CeAD cases and 14,416 controls. The rs9349379[G] allele (PHACTR1) was associated with lower CeAD risk (odds ratio (OR) = 0.75, 95% confidence interval (CI) = 0.69-0.82; P = 4.46 × 10(-10)), with confirmation in independent follow-up samples (659 CeAD cases and 2,648 controls; P = 3.91 × 10(-3); combined P = 1.00 × 10(-11)). The rs9349379[G] allele was previously shown to be associated with lower risk of migraine and increased risk of myocardial infarction. Deciphering the mechanisms underlying this pleiotropy might provide important information on the biological underpinnings of these disabling conditions