Genome-Wide Association Analysis of Major Depressive Disorder and Its Related Phenotypes.

Major Depressive Disorder (MDD) is a complex and chronic disease that ranks fourth as cause of disability worldwide. Thirteen to 14 million adults in the U.S. are believed to have MDD and an estimated 75% attempt suicide making MDD a major public health problem. Recently several genome-wide association (GWA) studies of MDD have been reported; however, few GWA studies focus on the analysis for MDD related phenotypes such as neuroticism and age at onset of MDD. The purpose of this study is to determine risk factors for MDD, identify genome-wide genetic variants affecting neuroticism and age at onset as quantitative traits, and detect gender differences influencing neuroticism. Bivariate and multiple logistic regression analyses were performed on 1,738 MDD cases and 1,618 non-MDD controls to determine phenotypic risk factors for MDD. Multiple linear regression analyses in PLINK software were used for GWA analyses for neuroticism and age at onset of MDD with 437,547 Single Nucleotide Polymorphisms (SNPs). Gender (OR: 1.43; 95% CI: 1.24 - 1.64) and a family history (OR: 2.88; 95% CI: 2.48 - 3.35) were significantly associated with an increased risk of MDD, which supports the findings of prior studies. Through GWA analysis 34 SNPs were identified to be associated with neuroticism (p \u3c 10-4). The best SNP was rs4806846 within the TMPRSS9 gene (p = 7.79 x10-6). Furthermore, 46 SNPs were found showing significant gene x gender interactions for neuroticism with p\u3c10-4. The best SNP showing gene x gender interaction was rs2430132 (p = 5.37x10-6) in HMCN1 gene. In addition, GWA analysis showed that several SNPs within 4 genes (GPR143, ASS1P4, MXRA5 and MAGEC1/2) were significantly associated with age at onset of MDD (p \u3c 5x10-7). This study confirmed previous findings that MDD is associated with an increased prevalence in women (about 43% more compared to men) and is highly heritable among first degree relatives. Several novel genetic loci were identified to be associated with neuroticism and age at onset. Gender differences were found in genetic influence of neuroticism. These findings offer the potential for new insights into the pathogenesis of MDD

BCL9 and C9orf5 are associated with negative symptoms in schizophrenia: meta-analysis of two genome-wide association studies

Schizophrenia is a chronic and debilitating psychiatric condition affecting slightly more than 1% of the population worldwide and it is a multifactorial disorder with a high degree of heritability (80%) based on family and twin studies. Increasing lines of evidence suggest intermediate phenotypes/endophenotypes are more associated with causes of the disease and are less genetically complex than the broader disease spectrum. Negative symptoms in schizophrenia are attractive intermediate phenotypes based on their clinical and treatment response features. Therefore, our objective was to identify genetic variants underlying the negative symptoms of schizophrenia by analyzing two genome-wide association (GWA) data sets consisting of a total of 1,774 European-American patients and 2,726 controls. Logistic regression analysis of negative symptoms as a binary trait (adjusted for age and sex) was performed using PLINK. For meta-analysis of two datasets, the fixed-effect model in PLINK was applied. Through meta-analysis we identified 25 single nucleotide polymorphisms (SNPs) associated with negative symptoms with p\u3c5×10(-5). Especially we detected five SNPs in the first two genes/loci strongly associated with negative symptoms of schizophrenia (P(meta-analysis)\u3c6.22×10(-6)), which included three SNPs in the BCL9 gene: rs583583 showed the strongest association at a P(meta-analysis) of 6.00×10(-7) and two SNPs in the C9orf5 (the top SNP is rs643410 with a p = 1.29 ×10(-6)). Through meta-analysis, we identified several additional negative symptoms associated genes (ST3GAL1, RNF144, CTNNA3 and ZNF385D). This is the first report of the common variants influencing negative symptoms of schizophrenia. These results provide direct evidence of using of negative symptoms as an intermediate phenotype to dissect the complex genetics of schizophrenia. However, additional studies are warranted to examine the underlying mechanisms of these disease-associated SNPs in these genes

Use of Massively Parallel Pyrosequencing to Evaluate the Diversity of and Selection on Plasmodium falciparum csp T-Cell Epitopes in Lilongwe, Malawi

The development of an effective malaria vaccine has been hampered by the genetic diversity of commonly used target antigens. This diversity has led to concerns about allele-specific immunity limiting the effectiveness of vaccines. Despite extensive genetic diversity of circumsporozoite protein (CS), the most successful malaria vaccine is RTS/S, a monovalent CS vaccine. By use of massively parallel pyrosequencing, we evaluated the diversity of CS haplotypes across the T-cell epitopes in parasites from Lilongwe, Malawi. We identified 57 unique parasite haplotypes from 100 participants. By use of ecological and molecular indexes of diversity, we saw no difference in the diversity of CS haplotypes between adults and children. We saw evidence of weak variant-specific selection within this region of CS, suggesting naturally acquired immunity does induce variant-specific selection on CS. Therefore, the impact of CS vaccines on variant frequencies with widespread implementation of vaccination requires further study

NTM and NR3C2 Polymorphisms Influencing Intelligence: Family-Based Association Studies

Family, twin, and adoption studies have indicated that human intelligence quotient (IQ) has significant genetic components. We performed a low-density genome-wide association analysis with a family-based association test to identify genetic variants influencing IQ, as measured by Wechsler Adult Intelligence Scale full-score IQ (FSIQ). We examined 11,120 single-nucleotide polymorphisms (SNPs) from the Affymetrix GeneChips 10K mapping array genotyped in 292 nuclear families from Genetic Analysis Workshop 14, a subset from the Collaborative Study on the Genetics of Alcoholism (COGA). A replication analysis was performed using part of International Multi-Center ADHD Genetics Project (IMAGE) dataset. Twenty-two SNPs were identified as having suggestive associations with IQ (p\u3c10-3) in the COGA sample and eleven of the SNPs were located within known genes. In particular, NTM at 11q25 (rs411280, p=0.000764) and NR3C2 at 4q31.1 (rs3846329, p=0.000675) were two novel genes which have not been associated with IQ in other studies. It has been reported that NTM might play a role in late-onset Alzheimer disease while NR3C2 may be associated with cognitive function and major depression. The associations of these two genes were well-replicated by single-marker and haplotype analyses in the IMAGE sample. In conclusion, our findings provide evidence that chromosome regions of 11q25 and 4q31.1 contain genes affecting IQ. This study will serve as a resource for replication in other populations

Genome-Wide Association Analysis of Gender Differences in Major Depressive Disorder in the Netherlands NESDA and NTR Population-Based Samples

Background: Major depressive disorder (MDD) is a universally prevalent, genetic, and environment dependent mental condition that disables people of every culture, race, gender, and age. While the gender differences for MDD have been widely reported in literature, few genome-wide analyses of gender differences have been reported to date. Methods: We conducted a genome-wide association analysis of gender differences for MDD using the Netherlands NESDA and NTR population-based samples (1726 cases and 1630 controls). PLINK software was used to analyze the genome-wide association data of Perlegen 600 K SNP Chips. Results: We identified 40 male-specific and 56 female-specific MDD associated SNPs with P-values less than 10- 4. The best male-specific SNP was rs9352774 (P = 2.26 × 10- 6) within LGSN gene while the best female-specific SNP was rs2715148 (P = 5.64 × 10- 7) within PCLO gene. We also found 38 SNPs showing gene × gender interactions in influencing MDD (P \u3c 10- 4). The best SNP was rs12692709 (P = 5.75 × 10- 6) near FIGN gene at 2q24.3 while the next best SNP was rs11039588 (P = 1.16 × 10- 5) within OR4B1 gene. Limitations: The findings from this study need be replicated in other populations. Conclusions: These results provide genetic basis for gender differences in MDD and will serve as a resource for replication in other populations to elucidate the potential role of these genetic variants in MDD

A Genome-Wide Meta-Analysis Identifies Novel Loci Associated With Schizophrenia and Bipolar Disorder

Schizophrenia and bipolar disorder both have strong inherited components. Recent studies have indicated that schizophrenia and bipolar disorder may share more than half of their genetic determinants. In this study, we performed a meta-analysis (combined analysis) for genome-wide association data of the Affymetrix Genome-Wide Human SNP array 6.0 to detect genetic variants influencing both schizophrenia and bipolar disorder using European-American samples (653 bipolar cases and 1034 controls, 1172 schizophrenia cases and 1379 controls). The best associated SNP rs11789399 was located at 9q33.1 (p=2.38×10-6, 5.74×10-4, and 5.56×10-9, for schizophrenia, bipolar disorder and meta-analysis of schizophrenia and bipolar disorder, respectively), where one flanking gene, ASTN2 (220kb away) has been associated with attention deficit/hyperactivity disorder and schizophrenia. The next best SNP was rs12201676 located at 6q15 (p=2.67×10-4, 2.12×10-5, 3.88×10-8 for schizophrenia, bipolar disorder and meta-analysis, respectively), near two flanking genes, GABRR1 and GABRR2 (15 and 17kb away, respectively). The third interesting SNP rs802568 was at 7q35 within CNTNAP2 (p=8.92×10-4, 1.38×10-5, and 1.62×10-7 for schizophrenia, bipolar disorder and meta-analysis, respectively). Through meta-analysis, we found two additional associated genes NALCN (the top SNP is rs2044117, p=4.57×10-7) and NAP5 (the top SNP is rs10496702, p=7.15×10-7). Haplotype analyses of above five loci further supported the associations with schizophrenia and bipolar disorder. These results provide evidence of common genetic variants influencing schizophrenia and bipolar disorder. These findings will serve as a resource for replication in other populations to elucidate the potential role of these genetic variants in schizophrenia and bipolar disorder

TMPRSS9 and GRIN2B Are Associated With Neuroticism: A Genome-Wide Association Study in a European Sample

Major depression disorder (MDD) is a complex and chronic disease that ranks fourth as cause of disability worldwide. About 14 million adults in the USA are believed to have MDD, and an estimated 75 % attempt suicide making MDD a major public health problem. Neuroticism has been recognized as an endophenotype of MDD; however, few genome-wide association (GWA) analyses of neuroticism as a quantitative trait have been reported to date. The aim of this study is to identify genome-wide genetic variants affecting neuroticism using a European sample. A linear regression model was used to analyze the association with neuroticism as a continuous trait in the Netherlands Study of Depression and Anxiety and Netherlands Twin Registry population-based sample of 2,748 individuals with Perlegen 600K single nucleotide polymorphisms (SNPs). In addition, the neuroticism-associated genes/loci of the top 20 SNPs (p \u3c 10-4) were examined with anti-social personality disorder (ASPD) in an Australian twin family study. Through GWA analysis, 32 neuroticism-associated SNPs (p \u3c 10-4) were identified. The most significant association was observed with SNP rs4806846 within the TMPRSS9 gene (p = 7.79 × 10-6) at 19p13.3. The next best signal was in GRIN2B gene (rs220549, p = 1.05 × 10-5) at 12p12. In addition, several SNPs within GRIN2B showed borderline associations with ASPD in the Australian sample. In conclusion, these results provide a possible genetic basis for the association with neuroticism. Our findings provide a basis for replication in other populations to elucidate the potential role of these genetic variants in neuroticism and MDD along with a possible relationship between ASPD and neuroticism

Genome-Wide Association Analysis of Age at Onset in Schizophrenia in a European-American Sample

We performed a genome-wide association analysis to identify genetic variants influencing age at onset (AAO) and examine gene×gender interactions for AAO in schizophrenia (SCZ) using a European-American sample (1,162 cases). Linear regression model in PLINK was used to test for associations with AAO while the GxE option was chosen to test for the influence of gene×gender interactions. The most significant association with AAO was observed with SNP rs7819815 (P=3.10×10-7) at 8q24.22. The next best signal was at 4q25 in COL25A1 gene (rs17039583, P=4.30×10-6) and the third region was at 4p16.1 (rs17407555, P=4.56×10-6, near RAF1P1, and rs4697924, P=1.23×10-5 within WDR1 gene). Conditional analysis on chromosome 4 indicated that 4p16.1 and 4q25 loci were independent. Furthermore, 2 SNPs (rs16834822 and rs16834824) at 1q43 in RYR2 showed strong associations in the female sample (P=2.10×10-6 and 2.33×10-6, respectively) and strong gene×gender interactions in influencing AAO (P=9.23×10-7 and 1.15×10-6, respectively) while the second best region showing gene×gender interaction was at 7q22.3 (rs179863, P=2.33×10-6). Using an independent sample of 1,068 cases, we could not replicate the associations for above top SNPs; however, we found nominal significance associations for their flanking SNPs (P\u3c0.05). These findings provide evidence of several genetic variants influencing AAO of SCZ

Parent-of-origin effects of FAS and PDLIM1 in attention-deficit/hyperactivity disorder

Background: Previous studies have suggested that there may be a parent-of-origin effect for attention-deficit/hyperactivity disorder (ADHD) candidate genes. The objective of the present study was to investigate parent-of-origin effects using a genome-wide association analysis of the International Multicentre ADHD Genetics (IMAGE) study sample. Methods: Family-based association analysis for ADHD using 846 ADHD probands and their parents was performed using the PLINK program, and parent-of-origin effects were studied using a Z score for the difference in paternal versus maternal odds ratios. Results: We identified 44 single nucleotide polymorphisms (SNPs) showing parent-of-origin effects at a significance level of p \u3c 0.001. The most significant SNP, rs7614907, is at position 3q13.33 in the CDGAP gene (p = 0.000064 for parent-of-origin effect). Furthermore, 2 genes (FAS and PDLIM1) showed moderate parent-of-origin effects (p = 0.00086 for rs9658691 and p = 0.00077 for rs11188249) and strong maternal transmission (p = 0.000059 for rs9658691 and p = 0.0000068 for rs11188249). In addition, ZNF775 showed a moderate parent-of-origin effect (p = 0.00036 for rs7790549) and strong paternal transmission (p = 0.000041 for rs7790549). Limitations: We only had 1 sample available for analysis. Conclusion: These results suggest several genes or regions with moderate parent-of-origin effects, and these findings will serve as a resource for replication in other populations to elucidate the potential role of these genetic variants in ADHD

A Meta-Analysis of Two Genome-Wide Association Studies Identifies 3 New Loci for Alcohol Dependence

Family, twin and adoption studies have clearly demonstrated that genetic factors are important in modulating the vulnerability to alcohol dependence. Several genome-wide association (GWA) studies of alcohol dependence have been conducted; however, few loci have been replicated. A meta-analysis was performed on two GWA studies of 1283 cases of alcohol dependence and 1416 controls in Caucasian populations. Through meta-analysis we identified 131 SNPs associated with alcohol dependence with p\u3c10-4. The best novel signal was rs6701037 (p=1.86 × 10-7) at 1q24-q25 within KIAA0040 gene while the second best novel hit was rs1869324 (p=4.71 × 10-7) at 2q22.1 within THSD7B. The third novel locus was NRD1 at 1p32.2 (the top SNP was rs2842576 with p=7.90 × 10-6). We confirmed the association of PKNOX2 at 11q24.4 with alcohol dependence. The top hit of PKNOX2 (rs750338 with p=1.47 × 10-6) in the meta-analysis was replicated with the Australian Twin-Family Study of 778 families (p=1.39 × 10-2) Furthermore, several flanking SNPs of the top hits in the meta-analysis demonstrated borderline associations with alcohol dependence in the family sample (top SNPs were rs2269655, rs856613, and rs10496768 with p=4.58 × 10-3, 2.1 × 10-4, and 2.86 × 10-3 for KIAA0040, NRD1 and THSD7B, respectively). In addition, ALK, CASC4, and SEMA5A were strongly associated with alcohol dependence (p\u3c2 × 10-5) in the meta-analysis. In conclusion, we identified three new loci (KIAA0040, THSD7B and NRD1) and confirmed the previous association of PKNOX2 with alcohol dependence. These findings offer the potential for new insights into the pathogenesis of alcohol dependence