Abstract The genomic organization and mRNA expression of the human GNAL gene on chromosome 18p11.2, a region that has been associated with bipolar disorder and schizophrenia, was determined. The GNAL gene was shown to span over 80 kb and consist of twelve exons, and its structure was very similar to adenyl cyclase stimulating G protein GSα. The start site of transcription was revealed by 5'-RACE. Two polyadenylation signals were found, and 3'-RACE assay was used to verify the functional site. The GNAL gene was expressed as approximately 6 kb transcripts in various regions of the human brain, and no alternative splicing was detected. One informative CA-dinucleotide repeat of 11 alleles and 74% heterozygosity was found in intron 5, and two single nucleotide polymorphisms in introns 3 and 10 were detected by SSCP. During characterization of the GNAL gene, two previously unknown genes were found. A novel intronless gene C18orf2 coding for a functionally unknown protein was localized to intron 5 of the GNAL gene. By semiquatitative RT-PCR, C18orf2 mRNA was found to be moderately expressed in all tissues studied here. Another novel gene, metallophosphoesterase MPPE1, was found to reside adjacent to the 3'-end of the GNAL gene in a tail-to-tail orientation. The deduced amino acid sequence revealed a highly conserved metallophosphoesterase motif gDxH..(16-60)..GDxxdr..(13-34)..GNH[DE], which is typical for various phosphate hydrolyzing enzymes, especially serine/threonine protein phosphatases. The MPPE1 gene contained fourteen exons and spanned about 27 kb. MPPE1 was expressed as a single mRNA of 2.2 kb in various regions of the human brain but not in any other tissues. Four different alternatively spliced forms of MPPE1 were detected by RT-PCR, and each transcript was shown to partially overlap with the 3'-untranslated region of the GNAL gene.

This dissertation is composed of five major chapters. The first is a comprehensiveliterature review, followed by three chapters of research findings, and a final concludingchapter. Major Depressive Disorder (MDD) is a phenotypically complex andheterogeneous syndrome. This challenge and others faced when investigating the geneticbasis for the susceptibility to MDD are discussed, as are tools used to address andovercome these challenges. Included in this review of the literature is a discussion onfindings of genome-wide analyses of MDD, as well as candidate genes that may play arole in the susceptibility to major depression. Following the literature review, threechapters of studies are presented. The first one demonstrates that in humans, the actualnumber of risk genotypes in the serotonin system accounts for over half of the variance inmood response to tryptophan depletion. There was no association between the dopaminesystem and mood response. The main conclusion from that study is that using a pathwayanalysis, rather than a single gene approach, may lead to more informative results whenstudying the genetics of a complex behavior. The next study demonstrates a similarconclusion, however, is not pathway specific. It is shown that in a group of de pressedsubjects not capable of treatment response, the mean number of risk genotypes is greaterthan in a group without depression. This supports the thought that treatment resistancemay be a more severe form of MDD. This study also presents data on single gene resultswhich demonstrate that the genetic basis for susceptibility to major depression may bedifferent and independent from the genetic basis for the capacity to respond to treatment.Several individual polymorphisms are implicated in each case. The final investigation is apublished manuscript refuting the findings of a previously published article onpolymorphisms in the TPH2 gene and association with treatment resistance. Many otherresearch groups have also been able to replicate the results demonstrated here. A finalchapter discusses the overall conclusions about the three research studies, as well as thefield of psychiatric genetics with a focus on the continuing search for the genetic basis ofsusceptibility to major depressive disorder.

Now is a time of dramatic change in mental health care as the world is witnessing a proliferation of research into the genetics of mental disorders. Despite several genetic test developments there is a paucity of qualitative research exploring the issues concerning its potential future introduction. This inspired my primary research question: What are the main implications regarding the developments being made in genetic testing for mental disorders in terms of their proposed introduction in a clinical setting? This was investigated through 33 semi-structured interviews with a range of psychiatric professionals from a single NHS trust location in the South West of England. As research has demonstrated that different medical professionals consider issues in mental health care in different ways (Colombo, et al. 2003 ; Fulford and Colombo, 2004) participants’ personal constructs of mental disorder were examined to see if their accounts of the tests differed on the basis of their unique conceptualisations of mental distress. An additional component feature in this research relates to what these developments may ultimately represent or provide psychiatry and mental health care as a result of being able to consider mental disorders in terms of underlying biology. Historically there has been a persistent attempt to determine the underlying genetic components of mental distress, however, this always seems to fail or the next big development is always ‘just around the corner’ - this observation is considered when the major developments in psychiatric genetics are examined in light of the sociological field of the ‘promissory nature of science’ (Borup, et al. 2006) - I suggest that the developments in genetic testing for mental distress represent an iconic continuation of this process. Interview transcripts were subjected to thematic analysis and five themes were developed that cover aspects such as how the tests’ introduction will alter perceptions in mental health care, issues concerning the tests’ practical impact, their possible shortcomings, and how they may alter clinical practice. My findings indicate that, in the majority of themes, personal approaches to mental disorder do appear to influence participants’ accounts of the tests. The overall trend is that if an interviewee personally endorsed a biological approach to understanding mental disorder they would be willing to see the tests used in clinical practice. There were two areas of thematic agreement between all psychiatric professionals regardless of their conceptualisations of mental disorder. These concerned the impacts genetic testing could have on different aspects of the legitimacy of mental disorders and the significance of using the tests to aid in treatment rather than diagnosis. Implications of my thematic findings for patient groups, mental health services, and policy makers are discussed.

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: see item for full text / AFRIKAANSE OPSOMMING: sien item vir volteks

Schizophrenia is one of our most common psychiatric diseases. It severely affects all aspects of psychological functions and results in loss of contact with reality. No cure exists and the treatments available today produce only partial relief for disease symptoms. The aim of this work is to better understand the etiology of schizophrenia by identification of candidate genes and gene pathways involved in the development of the disease. In a preliminarily study, the effects of medication and genetic factors were investigated in a candidate gene, serotonin 2C receptor. This study distinguished pharmacological effects, caused by neuroleptics, and/or genetic effects, caused by unique polymorphisms, from other effects responsible for mRNA expression changes on candidate genes. The core of the thesis describes a new candidate gene for schizophrenia, the quaking homolog, KH domain RNA binding (mouse) or QKI, located on chromosome 6q26-q27. The identification of QKI is supported by previous linkage studies, current association studies and mRNA expression studies using three different sample sets. The investigated samples included a 12-generation pedigree with 16 distantly related schizophrenic cases and their parents, 176 unrelated nuclear families with at least one affected child in each family and human brain autopsies from 55 schizophrenic cases and from 55 controls. Indirect evidence showing involvement of QKI in myelin regulation of central nervous system is presented. Myelin plays an important role in development of normal brains and disruption of QKI might lead to schizophrenia symptoms. In a forth sample set, including extended pedigrees originated from a geographically isolated area above the Arctic Circle, in northeast Sweden, two additional schizophrenia susceptibility loci were identified, 2q13 and 5q21. Both these regions have previously been highlighted as potential schizophrenia loci in several other investigations, including a large Finnish study. This suggests common schizophrenia susceptibility loci for Nordic populations. A pilot investigation including a genome wide haplotype analysis is presented. This statistical strategy could be further developed and applied to the artic Swedish families, including analysis of 900 microsatellites and 10,000 SNPs. These findings will facilitate the understanding of the schizophrenia etiology and may lead to development of more efficient treatments for patients that suffer from schizophrenia.

This thesis explores the subject positions available to users of genetic tests for bipolar disorder in the United States. In advanced liberal societies, tests for genetic susceptibility to complex disorders may be promoted and used as means of performing responsible citizenship through the consumption of health care services. In the context of mental illness, however, key assumptions about the characteristics of consumers may not be met. The research found that because the category of “potential test user” substantially overlaps with the category of “mental health care user,” both the rationality and autonomy of these individuals is subject to question. Test users are framed in relational terms: as family members, as patients, and as consumers – but the last of these relational frames is considered problematic. Therefore, while the tests are framed as tools for proactive health management, responsibilities surrounding their use are largely allocated to family members and doctors.

No description available.

Schizophrenia demonstrates high heritability in part accounted for by common simple nucleotide variants (SNV), rare copy number variants (CNV) and, most recently, rare SNVs Although heritability explained by rare SNVs and CNVs is small compared to that explained by common SNVs, rare SNVs in functional sequences may identify specific disease mechanisms. However, current exome methods do not capture a large proportion of potentially functional bases where rare variation may impact disease risk: as much as two-thirds of conserved sequences lie outside the exome in non-coding regions of cross-species evolutionary constraint. We reasoned that the candidate loci from the Psychiatric Genomics Consortium Phase 1 (PGC-1) schizophrenia study represent good target loci to test for the impact of rare SNVs in non-coding constrained regions. We developed custom reagents to capture mammalian constrained non-coding regions, exons, and 5’- and 3’-untranslated regions (UTRs) in the 12 PGC-1 loci for pooled sequencing in 912 cases and 936 controls. Compared to our coding targets, our noncoding targets contain substantially more highly conserved bases (46,412 vs. 31,609) and variants (390 vs. 193). Using C-alpha to detect excess variance due to aggregate risk increasing or decreasing rare SNV effects, we identified signals attributable to alleles with MAF < 0.1% in both coding sequences and in functional non-coding sequences, including variants within ENCODE transcription factor binding sites, DNase hypersensitive regions, and histone modification sites in neuronal cell lines. We also observed significant excess risk-altering variation in the CUB domain of CSMD1, a gene expressed in the developing central nervous system. These results support the hypothesis that common and rare variants in the same loci contribute to schizophrenia risk, but highlight the need to expand capture strategies in order to detect trait-relevant sequence variation in a broader set of functional sequences.

Alcohol Dependence (AD) is a chronic substance use disorder with moderate heritability (60%). Linkage and genome-wide association studies (GWAS) have implicated a number of loci; however, the molecular mechanisms underlying AD are unclear. Advances in systems biology allow genome-wide expression data to be integrated with genetic data to detect expression quantitative trait loci (eQTL), polymorphisms that regulate gene expression levels, influence phenotypes and are significantly enriched among validated genetic signals for many commonly studied traits including AD. We integrated genome-wide mRNA and miRNA expression data with genotypic data from the nucleus accumbens (NAc), a major addiction-related brain region, of 36 subjects (18 AD cases, 18 matched controls). We applied weighted gene co-expression network analysis (WGCNA) to identify mRNA and miRNA gene co-expression modules significantly associated with AD. We identified six mRNA modules, two of which were downregulated in AD and were enriched for neuronal marker gene expression. The remaining four modules were upregulated in AD and enriched for astrocyte and microglial marker gene expressions. After performing gene set enrichment analysis (GSEA), we found that neuronal-specific modules enriched for oxidative phosphorylation, mitochondrial dysfunction and MAPK signaling pathways and glial-specific modules enriched for immune related processes, cell adhesion molecules and cell signaling pathways. WGCNA was also applied to miRNA data and identified two downregulated and one upregulated modules in AD. We intersected computationally predicted miRNA:mRNA interactions with miRNA and mRNA expression correlations to identify 481 significant (FDR<0.10) miRNA:mRNA targeting pairs. Over half (54%) of the mRNAs were targeted cooperatively by more than one miRNA suggesting a potentially important cellular mechanism relevant to AD. After integrating our expression and genetic data we identified 591 significant mRNA and 68 significant miRNA cis-eQTLs (<1 megabase) (FDR<0.10). After querying against GWAS data from the Colaborative Study on Genetics of Alcohol and Study of Addiction: Gentics and Environment, eQTLs for neuronatin (NNAT; rs1780705), proteosome subunit type 5 (PSMB5; rs10137082), long non-coding RNA (PKI55; rs13392737), adaptor related protein complex 1 sigma one subunit (AP1S1; rs12079545) and translocation associate membrane protein 1 (TRAM1; rs13277972) were associated with AD or alcohol related phenotypes at p<10-4.

Obsessive-compulsive disorder (OCD) and the spectrum of associated conditions, affect 2-4% of the population worldwide. Although heritability studies in OCD have shown a 3 - 12 times increased risk for first degree relatives, the identification of the underlying risk-conferring genetic variation using classic genetic association studies has proven to be difficult. The possibility of a larger contribution of rare genetic variants to the risk of psychiatric disorder has been suggested by several successful studies. We expect that a spectrum of risk allele frequencies exists, which includes not only common variation but also a substantial amount of rare genetic variants that contribute to OCD. This thesis is aimed at identifying and functionally characterizing rare genetic variation in the OCD spectrum. Identified statistically significant variants were scrutinized for changes related to synaptic function using high content screening and subsequent functional analyses. Identifying the genetic profile of rare variants found in the OCD spectrum cohort combined with the functional impact that these variants have has provided insight into the etiology of the OCD spectrum. With these approaches a foundation can be laid for the development of a predictive model of the OCD spectrum.