Background: Alterations in the dopamine transmission and receptor density are hypothesized in the pathophysiology of schizophrenia but ethnic disparities are reported to exist in disease association and therapeutic response to psychotropic medication. Antipsychotics have higher binding affinity to D2 subtype of dopamine receptor. DRD2 Cys311, TaqIB1 and TaqIA1 variants are considered to have either reduced affinity for dopamine and hypo-dopaminergic activity.

BackgroundIntracranial aneurysm (IA) is often asymptomatic until the time of rupture resulting in subarachnoid hemorrhage (SAH).There is no precise biochemical or phenotype marker for diagnosis of aneurysm. Environmental risk factors that associate with IA can result in modifying the effect of inherited genetic factors and thereby increase the susceptibility to SAH. In addition subsequent to aneurismal rupture, the nature and quantum of inflammatory response might be critical for repair. Therefore, genetic liability to inflammatory response caused by polymorphisms in cytokine genes might be the common denominator for gene and environment in the development of aneurysm and complications associated with rupture.MethodsFunctionally relevant polymorphisms in the pro- and anti-inflammatory cytokine genes IL-1 complex (IL1A, IL1B, and IL1RN), TNFA, IFNG, IL3, IL6, IL12B, IL1RN, TGFB1, IL4, and IL10] were screened in radiologically confirmed 220 IA patients and 250 controls from genetically stratified Malayalam-speaking Dravidian ethnic population of south India. Subgroup analyses with genetic and environmental variables were also carried out.ResultsPro-inflammatory cytokines TNFA rs361525, IFNG rs2069718, and anti-inflammatory cytokine IL10 rs1800871 and rs1800872 were found to be significantly associated with IA, independent of epidemiological factors. TGFB1 rs1800469 polymorphism was observed to be associated with IA through co-modifying factors such as hypertension and gender. Functional prediction of all the associated SNPs of TNFA, IL10, and TGFB1 indicates their potential role in transcriptional regulation. Meta-analysis further reiterates that IL1 gene cluster and IL6 were not associated with IA.ConclusionsThe study suggests that chronic exposure to inflammatory response mediated by genetic variants in pro-inflammatory cytokines TNFA and IFNG could be a primary event, while stochastic regulation of IL10 and TGFB1 response mediated by comorbid factors such as hypertension may augment the pathogenesis of IA through vascular matrix degradation. The implication and interaction of these genetic variants under a specific environmental background will help us identify the resultant phenotypic variation in the pathogenesis of intracranial aneurysm. Identifying genetic risk factors for inflammation might also help in understanding and addressing the posttraumatic complications following the aneurismal rupture.Electronic supplementary materialThe online version of this article (doi:10.1186/s12974-015-0354-0) contains supplementary material, which is available to authorized users.

The extraction of genomic DNA is the crucial first step in large-scale epidemiological studies. Though there are many popular DNA isolation methods from human whole blood, only a few reports have compared their efficiencies using both end-point and real-time PCR assays. Genomic DNA was extracted from coronary artery disease patients using solution-based conventional protocols such as the phenol-chloroform/proteinase-K method and a non-phenolic non-enzymatic Rapid-Method, which were evaluated and compared vis-a-vis a commercially available silica column-based Blood DNA isolation kit. The appropriate method for efficiently extracting relatively pure DNA was assessed based on the total DNA yield, concentration, purity ratios (A/A and A/A), spectral profile and agarose gel electrophoresis analysis. The quality of the isolated DNA was further analysed for PCR inhibition using a murine specific ATP1A3 qPCR assay and mtDNA/Y-chromosome ratio determination assay. The suitability of the extracted DNA for downstream applications such as end-point SNP genotyping, was tested using PCR-RFLP analysis of the AGTR1-1166A>C variant, a mirSNP having pharmacogenetic relevance in cardiovascular diseases. Compared to the traditional phenol-chloroform/proteinase-K method, our results indicated the Rapid-Method to be a more suitable protocol for genomic DNA extraction from human whole blood in terms of DNA quantity, quality, safety, processing time and cost. The Rapid-Method, which is based on a simple salting-out procedure, is not only safe and cost-effective, but also has the added advantage of being scaled up to process variable sample volumes, thus enabling it to be applied in large-scale epidemiological studies.

Background: Aneurysmal subarachnoid hemorrhage (aSAH) has a mortality rate as high as 50%. The prevalence of intracranial aneurysms from various parts of India varies from 0.75 to 10.3%, with higher numbers of cases being diagnosed due to the increasing age of the population and improvements in imaging techniques. However, little is known about the attributable risk factors of aSAH in the Indian population. Methods: Using a case-control study we estimated the risk of factors such as hypertension, cigarette smoking, alcohol consumption, diabetes mellitus and family history of aSAH in a South Indian population. The population-attributable risk (PAR) of smoking, hypertension and alcohol use was estimated for the South Indian as well as for the general Indian population. Results: Our results showed that cigarette smoking (OR, 3.59; p < 0.001) and a history of hypertension (OR, 2.98; p < 0.001) were significant risk factors associated with aSAH. When patients were classified by gender, it was observed that being a smoker and having hypertension increased the risk for aSAH by nearly fourfold in men. Among women, hypertension and older age were significant risk factors. The PAR estimates indicated that smoking (OR, 3.59; 95% CI, 2.13–6.06) and hypertension (OR, 2.98; 95% CI, 1.73–5.12) are significant risk factors. Conclusions: Hypertension and smoking may be causal risk factors which might also modify the effect of genetic factors that could increase susceptibility to aSAH in the Indian population. Since these risk factors are amenable to effective modification, our findings will be useful for a gender-specific management of aSAH.

Serotonin (5-hydroxytryptamine (5-HT)) transporter (SLC6A4) is known to influence mood, emotion, cognition and efficacy of antidepressants, particularly that of selective serotonin reuptake inhibitors. Atypical antipsychotics exert their effects partially through serotinergic systems, and hence, variation in 5-HT uptake may affect antipsychotic action mediated through the serotinergic system. Therefore, investigating the role of SLC6A4 as a risk factor for developing schizophrenia and treatment response had been a point of concern for many investigators, but with variable outcome. In this study, we examined the genetic roles of five polymorphisms of SLC6A4, including those of the widely studied 44 base pair variable number of tandem repeat (VNTR) in the promoter region of SLC6A4 (the serotonin transporter gene-linked polymorphic region: 5HTTLPR) and a VNTR polymorphism (STin2) in the second intron, in schizophrenia and its influence on the severity of symptoms in a South Indian population from Kerala, comprising 586 individuals. We detected significant allelic and genotypic associations with rs2066713 (both allelic and genotypic P-value o0.001), 5HTTLPR (allelic P-value¼0.008 and genotypic P-value¼0.03) and STin2 polymorphisms (allelic P-value¼0.001 and genotypic P-value¼0.002). A haplotype linking these three risk alleles, 5HTTLPR/ S-rs2066713/C-STin2/12-repeat (P-value¼0.0059), was also significantly associated with disease in our population. Patients with STin2 12-repeat homozygotes showed a greater severity of blunted effect symptom. These results suggest a strong role of SLC6A4 in schizophrenia, possibly with a specific behavioral endophenotype in a South Indian population. Keywords: case-control; SLC6A4; schizophrenia; South India; symptom profile INTRODUCTION Schizophrenia is a common and complex psychiatric disorder, with proven genetic causes. Research to unravel the genetic basis of schizophrenia has revealed several molecules, including those involved in dopamine and serotonin neurotransmitter systems for the past few decades. Serotonin (5-hydroxytryptamine (5-HT)) hypothesis of schizophrenia has been reanalyzed with the effectiveness of clozapine, the best known atypical antipsychotic drug, 1 as an antagonist for several 5-HT receptors. 2,3 Moreover, 5-HT has been shown to regulate the development of the central nervous system. As the 5-HT transporter (5-HTT) regulates the 5-HT system, 4 alterations in the function of this protein could be involved in the development of schizophrenia. 5 The serotonin transporter (SLC6A4) gene spanning 37.8 kb is located on chromosome 17q11.2, 6,7 and has 14 exons encoding a protein of 630 amino acids. 8 SLC6A4 has received attention as a candidate in schizophrenia and mood disorders, owing to its influence on mood, emotion, cognition and also because 5-HTT is the principal site of action for some antidepressants, particularly for the selective

Intracranial aneurysm (IA) accounts for 85% of Subarachnoid Hemorrhage (SAH) and is mainly caused due to the weakening of arterial wall. The structural integrity of the intracranial arteries is mainly influenced by the extracellular matrix (ECM) remodeling. The Proteoglycan Versican plays an important role in extracellular matrix assembly and plays a major role in the pathogenesis of IA. The linkage studies also indicated VCAN as a putative candidate gene for IA in the 5q22–31 region. Using a case–control study design, we tested the hypothesis whether the variants in VCAN gene, nonsynonymous variants in the coding region of Glycosaminoglycan α (GAG-α) and GAG-β and two reported SNPs involved in splicing rs251124 and rs173686 can increase the risk of aSAH among South Indian patients, either independently, or by interacting with other risk factors of the disease. We selected 200 radiologically confirmed aneurysmal cases and 250 ethnically, age and sex matched controls from the Dravidian Malayalam speaking population of South India. The present study reiterated the earlier association of rs251124 with intracranial aneurysm (P = 0.0002) and also found a novel association with rs2287926 (G428D) in exon 7 coding for GAG-α with intracranial aneurysm (P = 0.0015). Interestingly, both these SNPs contributed to higher risk for aneurysm in males. In-silico analysis predicted this SNP to have the highest functional relevance in the gene which might have a potentially altered regulatory role in transcription and splicing. Using meta-analysis with available literature rs251124 was found to be the strongest intracranial aneurysm marker for global ethnicities. This study with a novel functional SNP rs2287926 (G428D) further substantiates the potential role of VCAN in the pathogenesis of IA.

Endothelial nitric oxide synthase (eNOS) gene polymorphisms have been implicated as predisposing genetic factors that can predict aneurysmal subarachnoid hemorrhage (aSAH), but with controversial results from different populations. Using a case-control study design, we tested the hypothesis whether variants in eNOS gene can increase risk of aSAH among South Indian patients, either independently, or by interacting with other risk factors of the disease. We enrolled 122 patients, along with 224 ethnically matched controls. We screened the intron-4 27-bp VNTR, the promoter T-786C and the exon-7 G894T SNPs in the eNOS gene. We found marked interethnic differences in the genotype distribution of eNOS variants when comparing the South Indian population with the reported frequencies from Caucasian and Japanese populations. Genotype distributions in control and patient populations were found to be in Hardy-Weinberg equilibrium. In patients, the allele, genotype and estimated haplotype frequencies did not differ significantly from the controls. Multiple logistic regression indicated hypertension and smoking as risk factors for the disease, however the risk alleles did not have any interaction with these risk factors. Although the eNOS polymorphisms were not found to be a likely risk factor for aSAH, the role of factors such as ethnicity, gender, smoking and hypertension should be evaluated cautiously to understand the genotype to phenotype conversion.

Intracranial aneurysm (IA) accounts for 85 % of haemorrhagic stroke and is mainly caused due to weakening of arterial wall. Lysyl oxidase (LOX) is a cuproenzyme involved in cross linking structural proteins collagen and elastin, thus providing structural stability to artery. Using a case-control study design, we tested the hypothesis whether the variants in LOX gene flanking the two LD block, can increase risk of aSAH among South Indian patients, either independently, or by interacting with other risk factors of the disease. SNPs were genotyped by fluorescence-based competitive allele-specific PCR (KASPar) chemistry. We selected 200 radiologically confirmed aneurysmal cases and 235 ethnically and age and gender matched controls from the Dravidian Malayalam speaking population of South India. We observed marked interethnic differences in the genotype distribution of LOX variants when compared to Japanese and African populations. However, there was no significant association with any of the LOX variants with IA. This study also could not observe any significant role of LOX polymorphisms in influencing IA either directly or indirectly through its confounding factors such as hypertension and gender in South Indian population.