On genes involved in common neurological disorders : focus on Parkinson's disease

Parkinson’s disease and migraine are complex neurological disorders and it is likely that a combination of genetic risk factors are involved in the etiology of both these diseases. Papers in this thesis investigate candidate genes in the search of genetic risk factors contributing to disease. Genetic research on Parkinson’s disease is extensive. Therefore, genes belonging to certain groups of risk-genes that are particularly interesting with regard to their function were selected for investigation in relation to this disease. We have performed association analyses alongside with gene expression and behavioral studies. Genetic variations in genes encoding detoxifying enzymes and genes involved in cellular processes of cell protection and survival have received special focus. We have also studied genes involved in mitochondrial function and genes linked to rare forms of hereditary Parkinson’s disease. A more recent approach in genetic studies has been to investigate genes shown to associate with or have close to significant p-values in genome wide association studies. In line with this, we have investigated major histocompability complex class II DR alpha (HLA-DRA), a gene connected to the immune-response, in our well characterized Parkinson’s disease case-control material. Through genetic analysis we have found evidence supportive of paraoxonase (PON) 1 and 2, mitochondrial translation initiation factor 3 (MTIF3), nuclear factor erythroid 2-like 2 (NRF2) and glucocerebrosidase (GBA) being associated with Parkinson’s disease. One single nucleotide polymorphism (SNP) in PON1 was associated with decreased risk of disease, while the other three genes were found to harbor SNPs and mutations conferring increased risk of Parkinson’s disease. The SNP in MTIF3 represents an expression quantitative trait locus and the presence of the minor allele was accompanied by a decrease in mRNA levels. Mitochondrial Ras homolog family (MIRO) 1 and 2, v-akt murine thymoma viral oncogene homolog 1 (AKT1) and HLA-DRA were also investigated, and shown not to associate with disease in our material. In spite of the lack of association with AKT1, we discovered that Parkinson patients had lower AKT1 gene expression, which we interpreted as a consequence of the constituent pathological conditions. We also studied alcohol dehydrogenase (ADH) genes and leucine-rich repeat kinase 2 (LRRK2) in animal models of Parkinson’s disease. We discovered that Lrrk2 and α-synuclein were co-regulated in the rodent striatum and that the lack of dopamine itself did not seem to influence the expression of these genes. In contrast, we found that absence of ADH genes, which are not expressed in the brain, could influence dopamine-dependent behavior in mice. Taken together, we have found evidence of involvement of all the targeted pathways and familial PD genes, with the exception of the immunological gene HLA-DRA. Little is known about the genetic relationships that might cause or influence the risk of migraine. Therefore we aimed to validate previously published genetic findings using microarray data in a well characterized Swedish cohort. Our study supports the involvement of genetic factors in migraine. We analyzed SNPs in eight candidate genes for migraine and our data are in favor of one SNP in PR domain containing 16 (PRDM16) and one SNP in the proximity of metadherin (MTDH) as risk factors for migraine in Sweden

Self-assembly of a silicon-containing side-chain liquid crystalline block copolymer in bulk and in thin films: kinetic pathway of a cylinder to sphere transition

The self-assembly of a high-χ silicon-containing side-chain liquid crystalline block copolymer (LC BCP) in bulk and in thin films is reported, and the structural transition process from the hexagonally packed cylinder (HEX) to the body-centered cubic structure (BCC) in thin films was examined by both reciprocal and real space experimental methods. The block copolymer, poly(dimethylsiloxane-b-11-(4′-cyanobiphenyl-4-yloxy)undecylmethacrylate) (PDMS-b-P(4CNB11C)MA) with a molecular weight of 19.5 kg mol−1 and a volume fraction of PDMS 27% self-assembled in bulk into a hierarchical nanostructure of sub-20 nm HEX cylinders of PDMS with the P(4CNB11C)MA block exhibiting a smectic LC phase with a 1.61 nm period. The structure remained HEX as the P(4CNB11C)MA block transformed to an isotropic phase at ∼120 °C. In the thin films, the PDMS cylindrical microdomains were oriented in layers parallel to the substrate surface. The LC block formed a smectic LC phase which transformed to an isotropic phase at ∼120 °C, and the microphase-separated nanostructure transformed from HEX to BCC spheres at ∼160 °C. The hierarchical structure as well as the dynamic structural transition of the thin films were characterized using in situ grazing-incidence small-angle X-ray scattering and grazing-incidence wide-angle X-ray scattering. The transient morphologies from the HEX to BCC structure in thin films were captured by scanning electron microscopy and atomic force microscopy, and the transition pathway was described.National Science Foundation (U.S.) (DMR-1606911)National Natural Science Foundation (China) (Grant 51403132)National Natural Science Foundation (China) (Grant 51773124

DJ-1 Mutations are Rare in a Swedish Parkinson Cohort

Mutations in the PARK7 gene, DJ-1, have been reported to cause early-onset and familial Parkinson’s disease (PD). The function of DJ-1 and how it contributes to the development of the disease is not clear today, but several studies report that DJ-1 is responsive to oxidative stress and important for the maintenance of mitochondria. We have screened three coding regions of DJ-1 (exon 2, 5 and 7) in a Swedish Parkinson cohort. The Swedish PD material consisted of 67 patients with a self reported positive family history of PD and 77 patients with early-onset of disease (≤50 years old). We detected two patients with the previously reported synonymous mutation, Ala167Ala (c.501A>G, rs71653621), in exon 7. No Ala167Ala carriers were identified among 213 neurologically healthy Swedish controls. Mechanisms by which the synonymous Ala167Ala mutation can have consequences are unknown. It may affect the mRNA stability, secondary structure of mRNA, synthesis, turnover, protein folding and function. We could show a 1.3% decrease in DJ-1 mRNA folding energy in the A<G substituted sequence compared to the wild type sequence in silico, suggesting a possible small effect of Ala167Ala on DJ-1 gene function. This is the first report on an identified DJ-1 mutation in Swedish PD patients. Our results, in combination with those of previous studies, strengthen the hypothesis that alterations in DJ-1 are not a common cause of familial and early-onset PD world-wide

Genetic Screening of the Mitochondrial Rho GTPases MIRO1 and MIRO2 in Parkinson’s Disease

MIRO1 and MIRO2 (mitochondrial Ras homolog gene family, member T1 and T2) also referred to as RHOT1 and RHOT2, belong to the mitochondrial Rho GTPase family and are involved in axonal transport of mitochondria in neurons. Because mitochondrial dysfunction is strongly implicated in Parkinson’s disease (PD), MIRO1 and MIRO2 can be considered as new candidate genes for PD. We analyzed two non-synonymous polymorphisms and one synonymous polymorphism in MIRO1 and two non-synonymous polymorphisms in MIRO2, in a Swedish Parkinson case-control material consisting of 241 patients and 307 neurologically healthy controls. None of the analyzed polymorphisms in MIRO1 and MIRO2 were significantly associated with PD. Although we did not find a significant association with PD in our Swedish case-control material, we cannot exclude these Rho GTPases as candidate genes for PD or other neurodegenerative disorders

Possible Involvement of a Mitochondrial Translation Initiation Factor 3 Variant Causing Decreased mRNA Levels in Parkinson's Disease

Genes important for mitochondrial function have been implicated in Parkinson's disease (PD). Mitochondrial translation initiation factor 3 (MTIF3) is a nuclear encoded protein required for the initiation of complex formation on mitochondrial ribosomes. Dysfunction of MTIF3 may impair mitochondrial function and dopamine neurons appear to be particularly vulnerable to oxidative stress, which may relate to their degeneration in PD. An association was recently reported between the synonymous rs7669(C>T) in MTIF3 and PD in a German case-control material. We investigated rs7669 in a Swedish Parkinson case-control material. The study revealed no significant association of the individual genotypes or alleles with PD. When comparing the combined TT/CT-genotypes versus the CC-genotype, we observed a significant association (P = .0473) with PD. We also demonstrated that the TT-genotype causes a significant decrease in MTIF3 mRNA expression compared to the CC-genotype (P = .0163). Our findings support the hypothesis that MTIF3 may be involved in the etiology of PD

Magnetization dynamics in optically excited nanostructured nickel films

In this work, Laser-induced magnetization dynamics of nanostructured nickel films is investigated. The influence of the nanosize is discussed considering the time-scale of hundreds of femtoseconds as well as the GHz regime. While no nanosize effect is observed on the short time-scale, the excited magnetic mode in the GHz regime can be identified by comparison with micromagnetic simulations. The thickness dependence reveals insight on the dipole interaction between single nickel structures. Also, transient reflectivity changes are discussed

Gene-environment correlations and causal effects of childhood maltreatment on physical and mental health: a genetically informed approach.

BACKGROUND: Childhood maltreatment is associated with poor mental and physical health. However, the mechanisms of gene-environment correlations and the potential causal effects of childhood maltreatment on health are unknown. Using genetics, we aimed to delineate the sources of gene-environment correlation for childhood maltreatment and the causal relationship between childhood maltreatment and health. METHODS: We did a genome-wide association study meta-analysis of childhood maltreatment using data from the UK Biobank (n=143 473), Psychiatric Genomics Consortium (n=26 290), Avon Longitudinal Study of Parents and Children (n=8346), Adolescent Brain Cognitive Development Study (n=5400), and Generation R (n=1905). We included individuals who had phenotypic and genetic data available. We investigated single nucleotide polymorphism heritability and genetic correlations among different subtypes, operationalisations, and reports of childhood maltreatment. Family-based and population-based polygenic score analyses were done to elucidate gene-environment correlation mechanisms. We used genetic correlation and Mendelian randomisation analyses to identify shared genetics and test causal relationships between childhood maltreatment and mental and physical health conditions. FINDINGS: Our meta-analysis of genome-wide association studies (N=185 414) identified 14 independent loci associated with childhood maltreatment (13 novel). We identified high genetic overlap (genetic correlations 0·24-1·00) among different maltreatment operationalisations, subtypes, and reporting methods. Within-family analyses provided some support for active and reactive gene-environment correlation but did not show the absence of passive gene-environment correlation. Robust Mendelian randomisation suggested a potential causal role of childhood maltreatment in depression (unidirectional), as well as both schizophrenia and ADHD (bidirectional), but not in physical health conditions (coronary artery disease, type 2 diabetes) or inflammation (C-reactive protein concentration). INTERPRETATION: Childhood maltreatment has a heritable component, with substantial genetic correlations among different operationalisations, subtypes, and retrospective and prospective reports of childhood maltreatment. Family-based analyses point to a role of active and reactive gene-environment correlation, with equivocal support for passive correlation. Mendelian randomisation supports a (primarily bidirectional) causal role of childhood maltreatment on mental health, but not on physical health conditions. Our study identifies research avenues to inform the prevention of childhood maltreatment and its long-term effects. FUNDING: Wellcome Trust, UK Medical Research Council, Horizon 2020, National Institute of Mental Health, and National Institute for Health Research Biomedical Research Centre.This work was supported by the Wellcome Trust (Grant refs: 214322/Z/18/Z, 104036/Z/14/Z, 204623/Z/16/Z, and 217065/Z/19/Z). VW was funded by the Bowring Research Fellowship from St. Catharine’s College, Cambridge and Wellcome Trust Collaborative Award (Grant Ref: 214322/Z/18/Z). ASFK and AM are supported by Wellcome Trust Grant 104036/Z/14/Z. ASFK is also supported by an ESRC Postdoctoral Fellowship (Grant ref: ES/V011650/1). ML is supported by the scholarship from the China Scholarship Council (No. 201706990036). The work of CC has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie grant agreement No 707404 and grant agreement No 848158 (EarlyCause Project). MHvIJ is supported by the Dutch Ministry of Education, Culture, and Science and the Netherlands Organization for Scientific Research (NWO grant No. 024.001.003, Consortium on Individual Development) and by a Spinoza Prize of the Netherlands Organization for Scientific Research. HMS and MRM are supported by the Medical Research Council and the University of Bristol (MC_UU_00011/7) and by the National Institute for Health Research (NIHR) Biomedical Research Centre at the University Hospitals Bristol National Health Service Foundation Trust and the University of Bristol. HMS is also supported by the European Research Council (Grant ref: 758813 MHINT). CMN is supported by the National Institute for Mental Health NIMH R01MH106595 and the Center of Excellence for Stress and Mental Health (CESAMH), Veterans Affairs San Diego. AJG and SB are supported by a Sir Henry Dale Fellowship jointly funded by the Wellcome Trust and the Royal Society (grant number 204623/Z/16/Z). TMM and RB are supported by the NIMH (R01MH117014, TMM; K23MH120437, RB).The research was conducted in association with the National Institute for Health Research (NIHR) Cambridge Biomedical Research Centre, and the NIHR Collaboration for Leadership in Applied Health Research and Care East of England at Cambridgeshire and Peterborough NHS Foundation Trust. The views expressed are those of the author(s) and not necessarily those of the National Health Service, the NIHR, or the Department of Health and Social Care. This research was possible due to two applications to the UK Biobank: Projects 20904 and 23787. This research was co-funded by the NIHR Cambridge Biomedical Research Centre and a Marmaduke Sheild grant. The UK Medical Research Council and Wellcome (Grant Ref: 217065/Z/19/Z) and the University of Bristol provide core support for ALSPAC. A comprehensive list of grants funding is available on the ALSPAC website (http://www.bristol.ac.uk/alspac/external/documents/grant-acknowledgements.pdf). We are extremely grateful to all the families who took part in this study, the midwives for their help in recruiting them, and the whole ALSPAC team, which includes interviewers, computer and laboratory technicians, clerical workers, research scientists, volunteers, managers, receptionists and nurses. The study website contains details of all data available through a fully searchable data dictionary (http://www.bristol.ac.uk/alspac/researchers/our-data/). Part of this data was collected using REDCap, see the REDCap website for details https://projectredcap.org/resources/citations/). The first phase of the Generation R Study is made possible by financial support from the Erasmus Medical Centre, Rotterdam; the Erasmus University Rotterdam; ZonMw; the Netherlands Organization for Scientific Research (NWO); and the Ministry of Health, Welfare and Sport. The authors gratefully acknowledge the contribution of all children and parents, general practitioners, hospitals, midwives and pharmacies involved in the Generation R Study. The Generation R Study is conducted by the Erasmus Medical Center in close collaboration with the School of Law and Erasmus School of Social and Behavioural Sciences at Erasmus University Rotterdam; the Municipal Health Service Rotterdam area, Rotterdam; the Rotterdam Homecare Foundation, Rotterdam; and the Stichting Trombosedienst & Artsenlaboratorium Rijnmond (STAR-MDC), Rotterdam

A new polygenic score for refractive error improves detection of children at risk of high myopia but not the prediction of those at risk of myopic macular degeneration

BACKGROUND: High myopia (HM), defined as a spherical equivalent refractive error (SER) ≤ -6.00 diopters (D), is a leading cause of sight impairment, through myopic macular degeneration (MMD). We aimed to derive an improved polygenic score (PGS) for predicting children at risk of HM and to test if a PGS is predictive of MMD after accounting for SER. METHODS: The PGS was derived from genome-wide association studies in participants of UK Biobank, CREAM Consortium, and Genetic Epidemiology Research on Adult Health and Aging. MMD severity was quantified by a deep learning algorithm. Prediction of HM was quantified as the area under the receiver operating curve (AUROC). Prediction of severe MMD was assessed by logistic regression. FINDINGS: In independent samples of European, African, South Asian and East Asian ancestry, the PGS explained 19% (95% confidence interval 17-21%), 2% (1-3%), 8% (7-10%) and 6% (3-9%) of the variation in SER, respectively. The AUROC for HM in these samples was 0.78 (0.75-0.81), 0.58 (0.53-0.64), 0.71 (0.69-0.74) and 0.67 (0.62-0.72), respectively. The PGS was not associated with the risk of MMD after accounting for SER: OR = 1.07 (0.92-1.24). INTERPRETATION: Performance of the PGS approached the level required for clinical utility in Europeans but not in other ancestries. A PGS for refractive error was not predictive of MMD risk once SER was accounted for. FUNDING: Supported by the Welsh Government and Fight for Sight (24WG201)

Common Variant Burden Contributes to the Familial Aggregation of Migraine in 1,589 Families

Complex traits, including migraine, often aggregate in families, but the underlying genetic architecture behind this is not well understood. The aggregation could be explained by rare, penetrant variants that segregate according to Mendelian inheritance or by the sufficient polygenic accumulation of common variants, each with an individually small effect, or a combination of the two hypotheses. In 8,319 individuals across 1,589 migraine families, we calculated migraine polygenic risk scores (PRS) and found a significantly higher common variant burden in familial cases (n = 5,317, OR = 1.76, 95% CI = 1.71-1.81, p = 1.7 × 10-109) compared to population cases from the FINRISK cohort (n = 1,101, OR = 1.32, 95% CI = 1.25-1.38, p = 7.2 × 10-17). The PRS explained 1.6% of the phenotypic variance in the population cases and 3.5% in the familial cases (including 2.9% for migraine without aura, 5.5% for migraine with typical aura, and 8.2% for hemiplegic migraine). The results demonstrate a significant contribution of common polygenic variation to the familial aggregation of migraine