Ajay Jajodia

Gender Specific Association of RAS Gene Polymorphism with Essential Hypertension: A Case-Control Study

Renin-angiotensin system (RAS) polymorphisms have been studied as candidate risk factors for hypertension with inconsistent results, possibly due to heterogeneity among various genetic and environmental factors. A case-control association study was conducted to investigate a possible involvement of polymorphisms of three RAS genes: AGT M235T (rs699), ACE I/D (rs4340) and G2350A (rs4343), and AGTR1 A1166C (rs5186) in essential hypertensive patients. A total of 211 cases and 211 controls were recruited for this study. Genotyping was performed using PCR-RFLP method. The genotype and allele distribution of the M235T variant differed significantly in hypertensives and normotensives (OR-CI = 2.62 (1.24–5.76), P = 0.006; OR-CI = 0.699 (0.518–0.943), P = 0.018), respectively. When the samples were segregated based on sex, the 235TT genotype and T allele were predominant in the female patients (OR-CI = 5.68 (1.60-25.10), P = 0.002; OR-CI = 0.522 (0.330–0.826), P = 0.005) as compare to the male patients (OR-CI = 1.54 (1.24–5.76), P = 0.34; OR-CI = 0.874 (0.330–0.826), P = 0.506), respectively. For ACE DD variant, we found overrepresentation of “I”-allele (homozygous II and heterozygous ID) in unaffected males which suggest its protective role in studied population (OR-CI = 0.401 (0.224–0.718); P = 0.0009). The M235T variant of the AGT is significantly associated with female hypertensives and ACE DD variant could be a risk allele for essential hypertension in south India.

Evidence for schizophrenia susceptibility alleles in the Indian population: An association of neurodevelopmental genes in case–control and familial samples

Schizophrenia is a severe psychiatric disorder with lifetime prevalence of ~1% worldwide. A genotyping study was conducted using a custom panel of Illumina 1536 SNPs in 840 schizophrenia cases and 876 controls (351 patients and 385 controls from North India; and 436 patients, 401 controls and 143 familial samples with 53 probands containing 37 complete and 16 incomplete trios from South India). Meta-analysis of this population of Indo-European and Dravidian ancestry identified three strongly associated variants with schizophrenia: STT3A (rs548181, p=1.47×10(-5)), NRG1 (rs17603876, p=8.66×10(-5)) and GRM7 (rs3864075, p=4.06×10(-3)). Finally, a meta-analysis was conducted comparing our data with data from the Schizophrenia Psychiatric Genome-Wide Association Study Consortium (PGC-SCZ) that supported rs548181 (p=1.39×10(-7)). In addition, combined analysis of sporadic case-control association and a transmission disequilibrium test in familial samples from South Indian population identified three associations: rs1062613 (p=3.12×10(-3)), a functional promoter variant of HTR3A; rs6710782 (p=3.50×10(-3)), an intronic variant of ERBB4; and rs891903 (p=1.05×10(-2)), an intronic variant of EBF1. The results support the risk variants observed in the earlier published work and suggest a potential role of neurodevelopmental genes in the schizophrenia pathogenesis.

Genetic studies indicate a potential target 5-HTR3B for Drug Therapy in Schizophrenia Patients†‡

Genetic Studies Indicate a Potential Target 5-HTR3B for Drug Therapy in Schizophrenia Patients Meenal Gupta, Sanjeev Jain, Nagaraj Moily, Harpreet Kaur, Ajay Jajodia, Meera Purushottam, and Ritushree Kukreti* Genomics and Molecular Medicine, Institute of Genomics and Integrative Biology (Council of Scientific and Industrial Research), Delhi, India Molecular Genetic Laboratory, Department of Psychiatry, National Institute of Mental Health and Neuro Sciences, Bangalore, India

Genetic variations of PIP4K2A confer vulnerability to poor antipsychotic response in severely ill schizophrenia patients.

Literature suggests that disease severity and neurotransmitter signaling pathway genes can accurately identify antipsychotic response in schizophrenia patients. However, putative role of signaling molecules has not been tested in schizophrenia patients based on severity of illness, despite its biological plausibility. In the present study we investigated the possible association of polymorphisms from five candidate genes RGS4, SLC6A3, PIP4K2A, BDNF, PI4KA with response to antipsychotic in variably ill schizophrenia patients. Thus in present study, a total 53 SNPs on the basis of previous reports and functional grounds were examined for their association with antipsychotic response in 423 schizophrenia patients segregated into low and high severity groups. Additionally, haplotype, diplotype, multivariate logistic regression and multifactor-dimensionality reduction (MDR) analyses were performed. Furthermore, observed associations were investigated in atypical monotherapy (nu200a=u200a355) and risperidone (nu200a=u200a260) treated subgroups. All associations were estimated as odds ratio (OR) and 95% confidence interval (CI) and test for multiple corrections was applied. Single locus analysis showed significant association of nine variants from SLC6A3, PIP4K2A and BDNF genes with incomplete antipsychotic response in schizophrenia patients with high severity. We identified significant association of six marker diplotype ATTGCT/ATTGCT (rs746203-rs10828317-rs7094131-rs2296624-rs11013052-rs1409396) of PIP4K2A gene in incomplete responders (corrected p-valueu200a=u200a0.001; adjusted-ORu200a=u200a3.19, 95%-CIu200a=u200a1.46–6.98) with high severity. These associations were further observed in atypical monotherapy and risperidone sub-groups. MDR approach identified gene-gene interaction among BDNF_rs7103411-BDNF_rs1491851-SLC6A3_rs40184 in severely ill incomplete responders (ORu200a=u200a7.91, 95%-CIu200a=u200a4.08–15.36). While RGS4_rs2842026-SLC6A3_rs2975226 interacted synergistically in incomplete responders with low severity (ORu200a=u200a4.09, 95%-CIu200a=u200a2.09–8.02). Our findings provide strong evidence that diplotype ATTGCT/ATTGCT of PIP4K2A gene conferred approximately three-times higher incomplete responsiveness towards antipsychotics in severely ill patients. These results are consistent with the known role of phosphatidyl-inositol-signaling elements in antipsychotic action and outcome. Findings have implication for future molecular genetic studies as well as personalized medicine. However more work is warranted to elucidate underlying causal biological pathway.

Identifying a predictive model for response to atypical antipsychotic monotherapy treatment in south Indian schizophrenia patients

Atypical antipsychotic (AAP) drugs are the preferred choice of treatment for schizophrenia patients. Patients who do not show favorable response to AAP monotherapy are subjected to random prolonged therapeutic treatment with AAP multitherapy, typical antipsychotics or a combination of both. Therefore, prior identification of patients response to drugs can be an important step in providing efficacious and safe therapeutic treatment. We thus attempted to elucidate a genetic signature which could predict patients response to AAP monotherapy. Our logistic regression analyses indicated the probability that 76% patients carrying combination of four SNPs will not show favorable response to AAP therapy. The robustness of this prediction model was assessed using repeated 10-fold cross validation method, and the results across n-fold cross-validations (mean accuracy=71.91%; 95%CI=71.47-72.35) suggest high accuracy and reliability of the prediction model. Further validations of these results in large sample sets are likely to establish their clinical applicability.

Evaluation of genetic association of neurodevelopment and neuroimmunological genes with antipsychotic treatment response in schizophrenia in Indian populations

Neurodevelopmental and neuroimmunological genes critically regulate antipsychotic treatment outcome. We report genetic associations of antipsychotic response in 742 schizophrenia patients from Indian populations of Indo‐European and Dravidian ancestry, segregated by disease severity. Meta‐analysis comparing the two populations identified CCL2 [rs4795893: OR (95% CI) = 1.79 (1.27–2.52), P = 7.62 × 10−4; rs4586: OR (95% CI) = 1.74 (1.24–2.43), P = 1.13 × 10−3] and GRIA4 [rs2513265: OR (95% CI) = 0.53 (0.36–0.78), P = 1.44 × 10−3] in low severity group; and, ADCY2 [rs1544938: OR (95% CI) = 0.36 (0.19–0.65), P = 7.68 × 10−4] and NRG1 [rs13250975, OR (95% CI) = 0.42 (0.23–0.79), P = 6.81 × 10−3; rs17716295, OR (95% CI) = 1.78 (1.15–2.75), P = 8.71 × 10−3] in high severity group, with incomplete response toward antipsychotics. To our knowledge, this is the first study to identify genetic polymorphisms associated with the efficacy of antipsychotic treatment of schizophrenia patients from two major India populations.

Methylation of a HTR3A promoter variant alters the binding of transcription factor CTCF

Genetic studies pertaining to effector molecules have been pivotal in schizophrenia research. The serotonin receptor HTR3A is an effector that plays a key role in schizophrenia development. Previously, we identified a promoter variant of HTR3A, rs1062613, to be associated with the disease in the Indian population. The present study was undertaken to dissect the possible functional role of rs1062613. Using in silico simulation and in vitro gel shift assays, the CCCTC-binding factor (CTCF) was found to bind at this variation site. A C/T polymorphism was found to affect the DNA binding of CTCF where CTCF binds less proficiently to the T-allele (alternate allele). Moreover, the binding was found to be dependent on methylation at the C-allele (reference allele). The CTCF was found to bind with a greater strength to methylated cytosine. A molecular dynamics simulation suggested the possible role of CTCF N-terminal in providing binding flexibility. Our results suggest the role of epigenetic mechanisms in the development of schizophrenia by modulating transcription factor binding.

Synergistic association of PI4KA and GRM3 genetic polymorphisms with poor antipsychotic response in south Indian schizophrenia patients with low severity of illness.

Literature indicates key role of glutamatergic pathway genes in antipsychotic response among schizophrenia patients. However, molecular basis of their underlying role in antipsychotic response remained unexplained. Thus, to unravel their molecular underpinnings, we sought to investigate interactions amongst GRM3, SLC1A1, SLC1A2, SLC1A3, SLC1A4 gene polymorphisms with drug response in south Indian schizophrenia patients. We genotyped 48 SNPs from these genes in 423 schizophrenia patients stratified into low and high severity of illness groups. The SNPs and haplotypic combinations of associated SNPs were examined for their association with antipsychotic response. Multifactor‐dimensionality‐reduction was further used to explore gene‐gene interaction among these SNPs and 53 SNPs from previously studied genes (BDNF, RGS4, SLC6A3, PI4KA, and PIP4K2A). Single SNP and haplotype analyses revealed no significant association with drug response irrespective of severity of illness. Gene‐gene interaction analyses yielded promising leads, including an observed synergistic effect between PI4KA_rs165854 and GRM3_rs1468412 polymorphisms and incomplete antipsychotic response in schizophrenia patients with low severity of illness (ORu2009=u200912.4; 95%CIu2009=u20093.69–41.69). Further, this interaction was also observed in atypical monotherapy (nu2009=u2009355) and risperidone (nu2009=u2009260) treatment subgroups (ORu2009=u200911.21; 95%CIu2009=u20093.30–38.12 and ORu2009=u200913.5; 95%CIu2009=u20093.03–121.61 respectively). PI4KA is known to be involved in the biosynthesis of phosphatidylinositol‐4, 5‐bisphosphate which regulates exocytotic fusion of synaptic vesicles (glutamate, dopamine) with the plasma membrane and regulates duration of signal transduction of GPCRs. Whereas GRM3 regulates glutamate and dopamine transmission. Present findings indicate that PI4KA and GRM3 polymorphisms have potential to jointly modulate antipsychotic response. These results warrant additional replication studies to shed further light on these interactions.

Exploring the Carbamazepine Interaction with Human Pregnane X Receptor and Effect on ABCC2 Using in Vitro and in Silico Approach

PurposeOver expression of ATP-binding cassette transporters is considered one of the major reasons for non-responsiveness to antiepileptic drugs. Carbamazepine (CBZ), one of first line antiepileptic drug is known to influence ABCC2 expression but its exact molecular mechanism is unknown.MethodsWe investigated the effect of CBZ on expression of ABCC2 and pregnane X receptor (PXR) in HepG2 cell line and compared with hyperforin (agonist of PXR) and ketoconazole (antagonist of PXR) through realtime PCR and western blot assay. Involvement of PXR was demonstrated through nuclear translocation and RNA interference and related effect of CBZ on ABCC2 through functional activity assay. Molecular docking and dynamic simulation approach was used to understand the interaction of CBZ with PXR.ResultsCBZ and hyperforin increased the PXR and ABCC2 expression whereas reversed when present it in combination with ketoconazole. Experiments confirmed CBZ induced ABCC2 expression is PXR dependent. Molecular dynamic (MD) simulation and in vitro experiment indicated possibility of CBZ to be PXR agonist and PXR residue Gln285 to be important for CBZ-PXR interaction.ConclusionsCBZ alters the functional activity of ABCC2 through PXR, which in turn can interfere with therapy. Mutational analysis of residues revealed the importance of Gln285 in ligand interaction.

Pharmacogenomics of neuropsychiatric disorders: analysis of genetic variability in 162 identified neuroreceptors using 1000 Genomes Project data

BACKGROUNDnNeuroreceptors are considered to be primary drug targets and their abrupt signaling is a notable cause of interindividual drug response variability and treatment failure for complex neuropsychiatric diseases. In view of recent evidence, it is believed that common genetic risk factors mainly highly polymorphic neuroreceptors are being shared among neuropsychiatric disorders.nnnMATERIALS & METHODSnWe identified 162 neuroreceptors from the 639 known receptors in Homo sapiens and investigated 231,683 SNPs using 1000 Genomes Project data and evaluated their biological effect using in silico tools including RegulomeDB, SIFT, PolyPhen-2 and CAROL. Furthermore, data from the 1000 Genomes Project was utilized to retrieve minor allele frequency and calculate pairwise logartithm of the odds score among these SNPs for African, American, Asian and European populations separately as well as when combined together using Haploview v4.2. LRTag was used to identify tagSNPs in populations.nnnRESULTSnA total of 52,381 (22.60%) SNPs were predicted as functionally important genetic variations. We identified sets of 603, 495, 450, 453 and 646 informative tagSNPs for African, American, Asian, European and combined populations, respectively. We propose construction of a neuroreceptor variants array with these informative SNPs for future pharmacogenomic studies of neuropsychiatric disorders.nnnCONCLUSIONnSuch an approach might improve genotype-phenotype correlation across different populations and lead to identification of reliable genetic markers and novel drug targets. Integration of these SNPs in literature would further provide evidence relevant to underlying mechanisms of genetics based nosology, pathophysiology and development of new drugs for the treatment of neuropsychiatric disorders.