Genome-wide association studies in neurological disorders

Evaluating Computer Vision, Large Language, and Genome-Wide Association Models in a Limited Sized Patient Cohort for Pre-Operative Risk Stratification in Adult Spinal Deformity Surgery

Background: Adult spinal deformities (ASD) are varied spinal abnormalities, often necessitating surgical intervention when associated with pain, worsening deformity, or worsening function. Predicting post-operative complications and revision surgery is critical for surgical planning and patient counseling. Due to the relatively small number of cases of ASD surgery, machine learning applications have been limited to traditional models (e.g., logistic regression or standard neural networks) and coarse clinical variables. We present the novel application of advanced models (CNN, LLM, GWAS) using complex data types (radiographs, clinical notes, genomics) for ASD outcome prediction. Methods: We developed a CNN trained on 209 ASD patients (1549 radiographs) from the Stanford Research Repository, a CNN pre-trained on VinDr-SpineXR (10,468 spine radiographs), and an LLM using free-text clinical notes from the same 209 patients, trained via Gatortron. Additionally, we conducted a GWAS using the UK Biobank, contrasting 540 surgical ASD patients with 7355 non-surgical ASD patients. Results: The LLM notably outperformed the CNN in predicting pulmonary complications (F1: 0.545 vs. 0.2881), neurological complications (F1: 0.250 vs. 0.224), and sepsis (F1: 0.382 vs. 0.132). The pre-trained CNN showed improved sepsis prediction (AUC: 0.638 vs. 0.534) but reduced performance for neurological complication prediction (AUC: 0.545 vs. 0.619). The LLM demonstrated high specificity (0.946) and positive predictive value (0.467) for neurological complications. The GWAS identified 21 significant (p < 10-5) SNPs associated with ASD surgery risk (OR: mean: 3.17, SD: 1.92, median: 2.78), with the highest odds ratio (8.06) for the LDB2 gene, which is implicated in ectoderm differentiation. Conclusions: This study exemplifies the innovative application of cutting-edge models to forecast outcomes in ASD, underscoring the utility of complex data in outcome prediction for neurosurgical conditions. It demonstrates the promise of genetic models when identifying surgical risks and supports the integration of complex machine learning tools for informed surgical decision-making in ASD.

Emerging concepts involving inhibitory and activating RNA functionalization towards the understanding of microcephaly phenotypes and brain diseases in humans

Microcephaly is characterized as a small head circumference, and is often accompanied by developmental disorders. Several candidate risk genes for this disease have been described, and mutations in non-coding regions are occasionally found in patients with microcephaly. Various non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), SINEUPs, telomerase RNA component (TERC), and promoter-associated lncRNAs (pancRNAs) are now being characterized. These ncRNAs regulate gene expression, enzyme activity, telomere length, and chromatin structure through RNA binding proteins (RBPs)-RNA interaction. Elucidating the potential roles of ncRNA-protein coordination in microcephaly pathogenesis might contribute to its prevention or recovery. Here, we introduce several syndromes whose clinical features include microcephaly. In particular, we focus on syndromes for which ncRNAs or genes that interact with ncRNAs may play roles. We discuss the possibility that the huge ncRNA field will provide possible new therapeutic approaches for microcephaly and also reveal clues about the factors enabling the evolutionary acquisition of the human-specific "large brain."

Exonic variants of the P2RX7 gene in familial multiple sclerosis

INTRODUCTION

Several studies have analysed the presence of P2RX7 variants in patients with MS, reporting diverging results.

METHODS

Our study analyses P2RX7 variants detected through whole-exome sequencing (WES).

RESULTS

We analysed P2RX7, P2RX4, and CAMKK2 gene variants detected by whole-exome sequencing in all living members (n = 127) of 21 families including at least 2 individuals with multiple sclerosis. P2RX7 gene polymorphisms previously associated with autoimmune disease. Although no differences were observed between individuals with and without multiple sclerosis, we found greater polymorphism of gain-of-function variants of P2RX7 in families with individuals with multiple sclerosis than in the general population. Copresence of gain-of-function and loss-of-function variants was not observed to reduce the risk of presenting the disease. Three families displayed heterozygous gain-of-function SNPs in patients with multiple sclerosis but not in healthy individuals. We were unable to determine the impact of copresence of P2RX4 and CAMKK2 variants with P2RX7 variants, or the potential effect of the different haplotypes described in the gene. No clinical correlations with other autoimmune diseases were observed in our cohort.

CONCLUSIONS

Our results support the hypothesis that the disease is polygenic and point to a previously unknown mechanism of genetic predisposition to familial forms of multiple sclerosis. P2RX7 gene activity can be modified, which suggests the possibility of preventive pharmacological treatments for families including patients with familial multiple sclerosis.

The Role of Genetic Ancestry as a Risk Factor for Primary Open-angle Glaucoma in African Americans

Purpose

POAG is the leading cause of irreversible blindness in African Americans. In this study, we quantitatively assess the association of autosomal ancestry with POAG risk in a large cohort of self-identified African Americans.

Methods

Subjects recruited to the Primary Open-Angle African American Glaucoma Genetics (POAAGG) study were classified as glaucoma cases or controls by fellowship-trained glaucoma specialists. POAAGG subjects were genotyped using the MEGA Ex array (discovery cohort, n = 3830; replication cohort, n = 2135). Population structure was interrogated using principal component analysis in the context of the 1000 Genomes Project superpopulations.

Results

The majority of POAAGG samples lie on an axis between African and European superpopulations, with great variation in admixture. Cases had a significantly lower mean value of the ancestral component q0 than controls for both cohorts (P = 6.14-4; P = 3-6), consistent with higher degree of African ancestry. Among POAG cases, higher African ancestry was also associated with thinner central corneal thickness (P = 2-4). Admixture mapping showed that local genetic ancestry was not a significant risk factor for POAG. A polygenic risk score, comprised of 23 glaucoma-associated single nucleotide polymorphisms from the NHGRI-EBI genome-wide association study catalog, was significant in both cohorts (P < 0.001), suggesting that both known POAG single nucleotide polymorphisms and an omnigenic ancestry effect influence POAG risk.

Conclusions

In sum, the POAAGG study population is very admixed, with a higher degree of African ancestry associated with an increased POAG risk. Further analyses should consider social and environmental factors as possible confounding factors for disease predisposition.

The Advantages and Challenges of Diversity in Pharmacogenomics: Can Minority Populations Bring Us Closer to Implementation?

Health disparities exist among minorities in the United States, with differences seen in disease prevalence, mortality, and responses to medications. These differences are multifactorial with genetic variation explaining a portion of this variability. Pharmacogenomics aims to find the effect of genetic variations on drug response, with the goal of optimizing drug therapy and development. Although genome-wide association studies have been useful in unbiasedly surveying the genome for genetic drivers of clinically relevant phenotypes, most of these studies have been conducted in mainly participants of European and Asian descent, contributing to a growing health disparity in precision medicine. Diversity is important to pharmacogenomic studies, and there may be real advantages to the use of these complex genomes in pharmacogenomics. In this review we will outline some of the advantages and confounders of pharmacogenomics in minorities, describe the role of genetic variation in pharmacologic pathways, and highlight a number of population-specific findings.

Exploring genetic targets of psoriasis using genome wide association studies (GWAS) for drug repurposing

Psoriasis is a chronic inflammatory disease causing itching in the body and pain in the joints. Currently, no permanent cure is available at a commercial level for this disease. Genome wide association studies (GWAS) provide a deeper insight that helps in better understanding this disease and further possible cure of this disease. The major goal of the present study is to identify potent genetic targets of psoriasis disease using GWAS approach and identify drugs for repurposing. The methods used include GWAS catalogue, GeneAnalytics, canSAR protein annotation tool, VarElect, Drug bank, Proteomics database, ProTox software. By exploring GWAS catalogue, 126 psoriasis associated genes (PAG) were identified. 68 genes found to be druggable were obtained from canSAR protein annotation tool. Localization results depict that maximum genes are present in cytoplasmic cellular components. The superpathways obtained from GeneAnalytics resulted in involvement of these genes in the immune system, Jak/Stat pathway, Th17 and Wnt pathways. Two genes Interleukin 13 (IL13) and POLI are Food and Drug Administration (FDA) approved targets. Small compounds for these targets were analysed for drug-likeliness, toxicity and mutagenecity properties. The FDA approved drug pandel was found to possess desirable properties. The medications used for psoriasis causes mild to severe side effects and does not work well always. Hence we propose drug repurposing strategy to use existing drugs for new therapies. Therefore, the drug pandel could be explored further and repurposed to treat psoriasis.

Exonic variants of genes related to the vitamin D signaling pathway in the families of familial multiple sclerosis using whole-exome next generation sequencing

INTRODUCTION

Vitamin D (VD) deficiency has been associated with multiple sclerosis (MS) and other autoimmune diseases (AIDs). However, the effect of the genetics of VD on the risk of MS is subject to debate. This study focuses on genes linked to the VD signaling pathway in families with MS. The evaluation of gene variants in all the members of families could contribute to an additional knowledge on the information obtained from case-control studies that use nonrelated healthy people.

MATERIAL AND METHODS

We studied 94 individuals from 15 families including at least two patients with MS. We performed whole-exome next generation sequencing on all individuals and analyzed variants of the DHCR7, CYP2R1, CYP3A4, CYP27A1, GC, CYP27B1, LRP2, CUBN, DAB2, FCGR, RXR, VDR, CYP24A1, and PDIA3 genes. We also studied PTH, FGF23, METTL1, METTL21B, and the role of the linkage disequilibrium block on the long arm of chromosome 12, through analysis of the CDK4, TSFM, AGAP2, and AVIL genes. We compared patients with MS, other AIDs and unaffected members from different family types.

RESULTS

The study described the variants in the VD signaling pathway that appear in families with at least two patients with MS. Some infrequent variants were detected in these families, but no significant difference was observed between patients with MS and/or other AIDs and unaffected family members in the frequency of these variants. Variants previously associated with MS in the literature were not observed in these families or were distributed similarly in patients and unaffected family members.

CONCLUSION

The study of genes involved in the VD signaling pathway in families that include more than one patient with MS did not identify any variants that could explain the presence of the disease, suggesting that VD metabolism could probably play a role in MS more as an environmental factor rather than as a genetic factor. Our study also supports the analysis of cases and unaffected individuals within families in order to determine the influence of genetic factors.

iMEGES: integrated mental-disorder GEnome score by deep neural network for prioritizing the susceptibility genes for mental disorders in personal genomes

BACKGROUND

A range of rare and common genetic variants have been discovered to be potentially associated with mental diseases, but many more have not been uncovered. Powerful integrative methods are needed to systematically prioritize both variants and genes that confer susceptibility to mental diseases in personal genomes of individual patients and to facilitate the development of personalized treatment or therapeutic approaches.

METHODS

Leveraging deep neural network on the TensorFlow framework, we developed a computational tool, integrated Mental-disorder GEnome Score (iMEGES), for analyzing whole genome/exome sequencing data on personal genomes. iMEGES takes as input genetic mutations and phenotypic information from a patient with mental disorders, and outputs the rank of whole genome susceptibility variants and the prioritized disease-specific genes for mental disorders by integrating contributions from coding and non-coding variants, structural variants (SVs), known brain expression quantitative trait loci (eQTLs), and epigenetic information from PsychENCODE.

RESULTS

iMEGES was evaluated on multiple datasets of mental disorders, and it achieved improved performance than competing approaches when large training dataset is available.

CONCLUSION

iMEGES can be used in population studies to help the prioritization of novel genes or variants that might be associated with the susceptibility to mental disorders, and also on individual patients to help the identification of genes or variants related to mental diseases.

MinION rapid sequencing: Review of potential applications in neurosurgery

BACKGROUND

Gene sequencing has played an integral role in the advancement and understanding of disease pathology and treatment. Although historically expensive and time consuming, new sequencing technologies improve our capability to obtain the genetic information in an accurate and timely manner. Within neurosurgery, gene sequencing is routinely used in the diagnosis and treatment of neurosurgical diseases, primarily for brain tumors. This paper reviews nanopore sequencing, an innovation utilized by MinION and outlines its potential use for neurosurgery.

METHODS

A literature search was conducted for publications containing the keywords of Oxford MinION, nanopore sequencing, brain tumor, glioma, whole genome sequencing (WGS), epigenomics, molecular neuropathology, and next-generation sequencing (NGS). In total, 64 articles were selected and used for this review.

RESULTS

The Oxford MinION nanopore sequencing technology has had successful applications within clinical microbiology, human genome sequencing, and cancer genotyping across multiple specialties. Technical details, methodology, and current use of MinION sequencing are discussed through the prism of potential applications to solve neurosurgery-related scientific and diagnostic questions. The MinION device has proven to provide rapid and accurate reads with longer read lengths when compared with NGS. For applications within neurosurgery, the MinION device is capable of providing critical diagnostic information for central nervous system (CNS) tumors within a single day.

CONCLUSIONS

MinION provides rapid and accurate gene sequencing with better affordability and convenience compared with current NGS methods. Widespread success of the MinION nanopore sequencing technology in providing accurate, rapid, and convenient gene sequencing suggests a promising future within research laboratories and to improve care for neurosurgical patients.

Evolving views of human genetic variation and its relationship to neurologic and psychiatric disease

Recent advances in exome and genome sequencing in populations are beginning to define the genetic architecture of neurologic and psychiatric disease. At the same time these findings are changing our perspective of genetic variant contributions to disease, implicating both rare and common genetic variation in common diseases. Most of what we know about genetic contributions to disease so far comes from analysis of mutations in protein-coding genes. Since most genetic variation lies in nonprotein-coding regions of the genome whose presumed function is entirely regulatory, understanding gene regulation in a cell type and developmental state-specific manner will be important to connect human genetic variation to disease mechanisms.

Role of Genetics and Epigenetics in the Pathogenesis of Alzheimer's Disease and Frontotemporal Dementia

Alzheimer's disease (AD) and frontotemporal dementia (FTD) represent the first cause of dementia in senile and pre-senile population, respectively. A percentage of cases have a genetic cause, inherited with an autosomal dominant pattern of transmission. The majority of cases, however, derive from complex interactions between a number of genetic and environmental factors. Gene variants may act as risk or protective factors. Their combination with a variety of environmental exposures may result in increased susceptibility to these diseases or may influence their course. The scenario is even more complicated considering the effect of epigenetics, which encompasses mechanisms able to alter the expression of genes without altering the DNA sequence. In this review, an overview of the current genetic and epigenetic progresses in AD and FTD will be provided, with particular focus on 1) causative genes, 2) genetic risk factors and disease modifiers, and 3) epigenetics, including methylation, non-coding RNAs and chromatin remodeling.

Two approaches reveal a new paradigm of 'switchable or genetics-influenced allele-specific DNA methylation' with potential in human disease

Imprinted genes are vulnerable to environmental influences during early embryonic development, thereby contributing to the onset of disease in adulthood. Monoallelic methylation at several germline imprints has been reported as DNMT1-dependent. However, which of these two epigenetic attributes, DNMT1-dependence or allelic methylation, renders imprinted genes susceptible to environmental stressors has not been determined. Herein, we developed a new approach, referred to as NORED, to identify 2468 DNMT1-dependent DNA methylation patterns in the mouse genome. We further developed an algorithm based on a genetic variation-independent approach (referred to as MethylMosaic) to detect 2487 regions with bimodal methylation patterns. Two approaches identified 207 regions, including known imprinted germline allele-specific methylation patterns (ASMs), that were both NORED and MethylMosaic regions. Examination of methylation in four independent mouse embryonic stem cell lines shows that two regions identified by both NORED and MethylMosaic (Hcn2 and Park7) did not display parent-of-origin-dependent allelic methylation. In these four F1 hybrid cell lines, genetic variation in Cast allele at Hcn2 locus introduces a transcription factor binding site for MTF-1 that may predispose Cast allelic hypomethylation in a reciprocal cross with either C57 or 129 strains. In contrast, each allele of Hcn2 ASM in J1 inbred cell line and Park7 ASM in four F1 hybrid cell lines seems to exhibit similar propensity to be either hypo- or hypermethylated, suggesting a ‘random, switchable’ ASM. Together with published results, our data on ASMs prompted us to propose a hypothesis of regional ‘autosomal chromosome inactivation (ACI)’ that may control a subset of autosomal genes. Therefore, our results open a new avenue to understand monoallelic methylation and provide a rich resource of candidate genes to examine in environmental and nutritional exposure models.

Brain transcriptome atlases: a computational perspective

The immense complexity of the mammalian brain is largely reflected in the underlying molecular signatures of its billions of cells. Brain transcriptome atlases provide valuable insights into gene expression patterns across different brain areas throughout the course of development. Such atlases allow researchers to probe the molecular mechanisms which define neuronal identities, neuroanatomy, and patterns of connectivity. Despite the immense effort put into generating such atlases, to answer fundamental questions in neuroscience, an even greater effort is needed to develop methods to probe the resulting high-dimensional multivariate data. We provide a comprehensive overview of the various computational methods used to analyze brain transcriptome atlases.

The genetic background of Parkinson's disease: current progress and future prospects

Almost two decades of genetic research in Parkinson's disease (PD) have remarkably increased our knowledge regarding the genetic basis of PD with numerous genes and genetic loci having been found to cause familial PD or affect the risk for PD. Approximately 5-10% of PD patients have monogenic forms of the disease, exhibiting a classical Mendelian type of inheritance, however, the majority PD cases are sporadic, probably caused by a combination of genetic and environmental risk factors. Nowadays, six genes, alpha synuclein, LRRK2, VPS35, Parkin, PINK1 and DJ-1, have definitely been associated with an autosomal dominant or recessive PD mode of inheritance. The advent of genome-wide association studies (GWAS) and the implementation of new technologies, like next generation sequencing (NGS) and exome sequencing has undoubtedly greatly aided the identification on novel risk variants for sporadic PD. In this review, we will summarize the current progress and future prospects in the field of PD genetics.

Identification of long non-coding RNAs involved in neuronal development and intellectual disability

Recently, exome sequencing led to the identification of causal mutations in 16–31% of patients with intellectual disability (ID), leaving the underlying cause for many patients unidentified. In this context, the noncoding part of the human genome remains largely unexplored. For many long non-coding RNAs (lncRNAs) a crucial role in neurodevelopment and hence the human brain is anticipated. Here we aimed at identifying lncRNAs associated with neuronal development and ID. Therefore, we applied an integrated genomics approach, harnessing several public epigenetic datasets. We found that the presence of neuron-specific H3K4me3 confers the highest specificity for genes involved in neurodevelopment and ID. Based on the presence of this feature and GWAS hits for CNS disorders, we identified 53 candidate lncRNA genes. Extensive expression profiling on human brain samples and other tissues, followed by Gene Set Enrichment Analysis indicates that at least 24 of these lncRNAs are indeed implicated in processes such as synaptic transmission, nervous system development and neurogenesis. The bidirectional or antisense overlapping orientation relative to multiple coding genes involved in neuronal processes supports these results. In conclusion, we identified several lncRNA genes putatively involved in neurodevelopment and CNS disorders, providing a resource for functional studies.

Genetic manipulation for inherited neurodegenerative diseases: myth or reality?

Rare genetic diseases affect about 7% of the general population and over 7000 distinct clinical syndromes have been described with the majority being due to single gene defects. This review will provide a critical overview of genetic strategies that are being pioneered to halt or reverse disease progression in inherited neurodegenerative diseases. This field of research covers a vast area and only the most promising treatment paradigms will be discussed with a particular focus on inherited eye diseases, which have paved the way for innovative gene therapy paradigms, and mitochondrial diseases, which are currently generating a lot of debate centred on the bioethics of germline manipulation.

Functional genomics of candidate genes derived from genome-wide association studies for five common neurological diseases

AIM

Recent genome-wide association studies (GWAS) are identifying novel candidate genes for several neurological diseases (NDs). However, a global functional analysis of those genes derived from GWAS for NDs is missing. We explored the genomic and functional features of novel candidate genes for five common NDs: Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, stroke and migraine.

MATERIALS AND METHODS

A functional enrichment analysis was performed for GWAS-derived genes, for categories such as Kyoto Encyclopedia of Genes and Genomes pathways, gene expression, InterPro domains, transcription factor binding sites, gene ontology (GO) terms and microRNA (miRNA) targets. An analysis of protein-protein interactions was carried out.

RESULTS

Six hundred and forty-two unique single nucleotide polymorphisms (SNPs) were identified for the five NDs and 2.3% of them were non-synonymous SNPs. There were no common SNPs for all five NDs and eight genes were associated with more than one ND. The enrichment analysis showed significant values for several GO categories, such as cell-cell adhesion and location in neurites and for expression in prefrontal cortex. An analysis of protein-protein interactions showed the evidence of a large component. Fifty-one of these GWAS-derived genes are known to be potentially druggable and twelve are known to harbor mutations for neuropsychiatric disorders.

CONCLUSIONS

Our results suggest that there is little overlap between the genes identified in GWAS for the five common NDs. Identification of functional categories in the GWAS-derived candidate genes for common NDs could lead to a better understanding of their functional consequences and could be useful for the future discovery of additional genetic risk factors for those diseases.

SNPs Array Karyotyping in Non-Hodgkin Lymphoma

The traditional methods for detection of chromosomal aberrations, which included cytogenetic or gene candidate solutions, suffered from low sensitivity or the need for previous knowledge of the target regions of the genome. With the advent of single nucleotide polymorphism (SNP) arrays, genome screening at global level in order to find chromosomal aberrations like copy number variants, DNA amplifications, deletions, and also loss of heterozygosity became feasible. In this review, we present an update of the knowledge, gained by SNPs arrays, of the genomic complexity of the most important subtypes of non-Hodgkin lymphomas.

Cbl-b-deficient mice express alterations in trafficking-related molecules but retain sensitivity to the multiple sclerosis therapeutic agent, FTY720

The variable response to therapy in multiple sclerosis (MS) suggests a need for personalized approaches based on individual genetic differences. GWAS have linked CBLB gene polymorphisms with MS and recent evidence demonstrated that these polymorphisms can be associated with abnormalities in T cell function and response to interferon-β therapy. Cbl-b is an E3 ubiquitin ligase that regulates T cell activation and Cbl-b-deficient (Cbl-b(-/-)) mice show T cell abnormalities described in MS patients. We now show that Cbl-b(-/-) T cells demonstrate significant lymph node trafficking abnormalities. We thus asked whether the MS-approved drug, FTY720, postulated to trap T cells in lymphoid tissues, is less effective in the context of Cbl-b dysfunction. We now report that FTY720 significantly inhibits EAE in Cbl-b(-/-) mice. Our results newly document a role for Cbl-b in T cell trafficking but suggest nevertheless that MS patients with Cbl-b abnormalities may still be excellent candidates for FTY720 treatment.

Application of next-generation sequencing technologies in Neurology

Genetic risk factors that underlie many rare and common neurological diseases remain poorly understood because of the multi-factorial and heterogeneous nature of these disorders. Although genome-wide association studies (GWAS) have successfully uncovered numerous susceptibility genes for these diseases, odds ratios associated with risk alleles are generally low and account for only a small proportion of estimated heritability. These results implicated that there are rare (present in <5% of the population) but not causative variants exist in the pathogenesis of these diseases, which usually have large effect size and cannot be captured by GWAS. With the decreasing cost of next-generation sequencing (NGS) technologies, whole-genome sequencing (WGS) and whole-exome sequencing (WES) have enabled the rapid identification of rare variants with large effect size, which made huge progress in understanding the basis of many Mendelian neurological conditions as well as complex neurological diseases. In this article, recent NGS-based studies that aimed to investigate genetic causes for neurological diseases, including Alzheimer's disease, Parkinson's disease, epilepsy, multiple sclerosis, stroke, amyotrophic lateral sclerosis and spinocerebellar ataxias, have been reviewed. In addition, we also discuss the future directions of NGS applications in this article.

Genome-wide association studies in Africans and African Americans: expanding the framework of the genomics of human traits and disease

Genomic research is one of the tools for elucidating the pathogenesis of diseases of global health relevance and paving the research dimension to clinical and public health translation. Recent advances in genomic research and technologies have increased our understanding of human diseases, genes associated with these disorders, and the relevant mechanisms. Genome-wide association studies (GWAS) have proliferated since the first studies were published several years ago and have become an important tool in helping researchers comprehend human variation and the role genetic variants play in disease. However, the need to expand the diversity of populations in GWAS has become increasingly apparent as new knowledge is gained about genetic variation. Inclusion of diverse populations in genomic studies is critical to a more complete understanding of human variation and elucidation of the underpinnings of complex diseases. In this review, we summarize the available data on GWAS in recent African ancestry populations within the western hemisphere (i.e. African Americans and peoples of the Caribbean) and continental African populations. Furthermore, we highlight ways in which genomic studies in populations of recent African ancestry have led to advances in the areas of malaria, HIV, prostate cancer, and other diseases. Finally, we discuss the advantages of conducting GWAS in recent African ancestry populations in the context of addressing existing and emerging global health conditions.

A multiple sclerosis-associated variant of CBLB links genetic risk with type I IFN function

Multiple sclerosis (MS) is an autoimmune disease of the CNS, and autoreactive CD4(+) T cells are considered important for its pathogenesis. The etiology of MS involves a complex genetic trait and environmental triggers that include viral infections, particularly the EBV. Among the risk alleles that have repeatedly been identified by genome-wide association studies, three are located near the Casitas B-lineage lymphoma proto-oncogene b gene (CBLB). The CBLB protein (CBL-B) is a key regulator of peripheral immune tolerance by limiting T cell activation and expansion and hence T cell-mediated autoimmunity through its ubiquitin E3-ligase activity. In this study, we show that CBL-B expression is reduced in CD4(+) T cells from relapsing-remitting MS (RR-MS) patients during relapse. The MS risk-related single nucleotide polymorphism of CBLB rs12487066 is associated with diminished CBL-B expression levels and alters the effects of type I IFNs on human CD4(+) T cell proliferation. Mechanistically, the CBLB rs12487066 risk allele mediates increased binding of the transcription factor C/EBPβ and reduced CBL-B expression in human CD4(+) T cells. Our data suggest a role of the CBLB rs12487066 variant in the interactions of a genetic risk factor and IFN function during viral infections in MS.

Emerging epigenetic mechanisms of long non-coding RNAs

Long non-coding RNAs (lncRNAs) have been increasingly appreciated as an integral component of gene regulatory networks. Genome-wide features of their origin and expression patterns ascribed a prominent role for lncRNAs to the regulation of protein-coding genes, and also suggest a potential link to many human diseases. Recent studies have begun to unravel the intricate regulatory mechanism of lncRNAs occurring at multiple levels. The brain is one of the richest sources of lncRNAs, many of which have already shown a close relationship with genes or genetic loci implicated in a wide range of neurological disorders. This review describes recently emerging mechanistic principles of lncRNA functions to provide neuroscientists with molecular insights that will help future research on lncRNAs in the brain.

Pathways to neurodegeneration: mechanistic insights from GWAS in Alzheimer's disease, Parkinson's disease, and related disorders

The discovery of causative genetic mutations in affected family members has historically dominated our understanding of neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), frontotemporal dementia (FTD), and amyotrophic lateral sclerosis (ALS). Nevertheless, most cases of neurodegenerative disease are not explained by Mendelian inheritance of known genetic variants, but instead are thought to have a complex etiology with numerous genetic and environmental factors contributing to susceptibility. Although unbiased genome-wide association studies (GWAS) have identified novel associations to neurodegenerative diseases, most of these hits explain only modest fractions of disease heritability. In addition, despite the substantial overlap of clinical and pathologic features among major neurodegenerative diseases, surprisingly few GWAS-implicated variants appear to exhibit cross-disease association. These realities suggest limitations of the focus on individual genetic variants and create challenges for the development of diagnostic and therapeutic strategies, which traditionally target an isolated molecule or mechanistic step. Recently, GWAS of complex diseases and traits have focused less on individual susceptibility variants and instead have emphasized the biological pathways and networks revealed by genetic associations. This new paradigm draws on the hypothesis that fundamental disease processes may be influenced on a personalized basis by a combination of variants - some common and others rare, some protective and others deleterious - in key genes and pathways. Here, we review and synthesize the major pathways implicated in neurodegeneration, focusing on GWAS from the most prevalent neurodegenerative disorders, AD and PD. Using literature mining, we also discover a novel regulatory network that is enriched with AD- and PD-associated genes and centered on the SP1 and AP-1 (Jun/Fos) transcription factors. Overall, this pathway- and network-driven model highlights several potential shared mechanisms in AD and PD that will inform future studies of these and other neurodegenerative disorders. These insights also suggest that biomarker and treatment strategies may require simultaneous targeting of multiple components, including some specific to disease stage, in order to assess and modulate neurodegeneration. Pathways and networks will provide ideal vehicles for integrating relevant findings from GWAS and other modalities to enhance clinical translation.

Effectiveness of a web-based protocol for the screening and phenotyping of individuals with Tourette syndrome for genetic studies

Genome-wide association studies (GWAS) and other emerging technologies offer great promise for the identification of genetic risk factors for complex psychiatric disorders, yet such studies are constrained by the need for large sample sizes. Web-based collection offers a relatively untapped resource for increasing participant recruitment. Therefore, we developed and implemented a novel web-based screening and phenotyping protocol for genetic studies of Tourette syndrome (TS), a childhood-onset neuropsychiatric disorder characterized by motor and vocal tics. Participants were recruited over a 13-month period through the membership of the Tourette Syndrome Association (TSA; n = 28,878). Of the TSA members contacted, 4.3% (1,242) initiated the questionnaire, and 79.5% (987) of these were enrollment eligible. 63.9% (631) of enrolled participants completed the study by submitting phenotypic data and blood specimens. Age was the only variable that predicted study completion; children and young adults were significantly less likely to be study completers than adults 26 and older. Compared to a clinic-based study conducted over the same time period, the web-based method yielded a 60% larger sample. Web-based participants were older and more often female; otherwise, the sample characteristics did not differ significantly. TS diagnoses based on the web-screen demonstrated 100% accuracy compared to those derived from in-depth clinical interviews. Our results suggest that a web-based approach is effective for increasing the sample size for genetic studies of a relatively rare disorder and that our web-based screen is valid for diagnosing TS. Findings from this study should aid in the development of web-based protocols for other disorders.

Serum granulocyte colony-stimulating factor and Alzheimer's disease

Background

Granulocyte colony-stimulating factor (G-CSF) promotes the survival and function of neutrophils. G-CSF is also a neurotrophic factor, increasing neuroplasticity and suppressing apoptosis.

Methods

We analyzed G-CSF levels in 197 patients with probable Alzheimer's disease (AD) and 203 cognitively normal controls (NCs) from a longitudinal study by the Texas Alzheimer's Research and Care Consortium (TARCC). Data were analyzed by regression with adjustment for age, education, gender and APOE4 status.

Results

Serum G-CSF was significantly lower in AD patients than in NCs (β = −0.073; p = 0.008). However, among AD patients, higher serum G-CSF was significantly associated with increased disease severity, as indicated by lower Mini-Mental State Examination scores (β = −0.178; p = 0.014) and higher scores on the global Clinical Dementia Rating (CDR) scale (β = 0.170; p = 0.018) and CDR Sum of Boxes (β = 0.157; p = 0.035).

Conclusions

G-CSF appears to have a complex relationship with AD pathogenesis and may reflect different pathophysiologic processes at different illness stages.

The genetic architecture of Alzheimer's disease: beyond APP, PSENs and APOE

Alzheimer's disease (AD) is a complex disorder with a clear genetic component. Three genes have been identified as the cause of early onset familial AD (EOAD). The most common form of the disease, late onset Alzheimer's disease (LOAD), is, however, a sporadic one presenting itself in later stages of life. The genetic component of this late onset form of AD has been the target of a large number of studies, because only one genetic risk factor (APOE4) has been consistently associated with the disease. However, technological advances allow new approaches in the study of complex disorders. In this review, we discuss the new results produced by genome wide association studies, in light of the current knowledge of the complexity of AD genetics.

Newly diagnosed epilepsy and pharmacogenomics research: a step in the right direction?

Pharmacogenomics holds the promise of selecting the right drug at the right dose for the right person. Its research and application in epilepsy are in their infancy. Although advances have been made in identifying genetic markers of adverse effects in terms of severe cutaneous reactions, there has been little progress in predicting efficacy. Most studies have been retrospective and case-control in design, despite the associated problems of recall bias and a usually undefined relationship between genotype and outcome. We describe the epidemiological framework necessary to detect genetic influences on antiepileptic drug response, and propose an ambitious prospective outcome study of newly diagnosed epilepsy across all age ranges, countries, and continents, which would provide the template for a global pharmacogenomic project. Other epidemiological considerations and statistical constraints and issues related to study design, databases, and ethics that are critical for advancement in the field are also discussed.

Gene expression endophenotypes: a novel approach for gene discovery in Alzheimer's disease

Uncovering the underlying genetic component of any disease is key to the understanding of its pathophysiology and may open new avenues for development of therapeutic strategies and biomarkers. In the past several years, there has been an explosion of genome-wide association studies (GWAS) resulting in the discovery of novel candidate genes conferring risk for complex diseases, including neurodegenerative diseases. Despite this success, there still remains a substantial genetic component for many complex traits and conditions that is unexplained by the GWAS findings. Additionally, in many cases, the mechanism of action of the newly discovered disease risk variants is not inherently obvious. Furthermore, a genetic region with multiple genes may be identified via GWAS, making it difficult to discern the true disease risk gene. Several alternative approaches are proposed to overcome these potential shortcomings of GWAS, including the use of quantitative, biologically relevant phenotypes. Gene expression levels represent an important class of endophenotypes. Genetic linkage and association studies that utilize gene expression levels as endophenotypes determined that the expression levels of many genes are under genetic influence. This led to the postulate that there may exist many genetic variants that confer disease risk via modifying gene expression levels. Results from the handful of genetic studies which assess gene expression level endophenotypes in conjunction with disease risk suggest that this combined phenotype approach may both increase the power for gene discovery and lead to an enhanced understanding of their mode of action. This review summarizes the evidence in support of gene expression levels as promising endophenotypes in the discovery and characterization of novel candidate genes for complex diseases, which may also represent a novel approach in the genetic studies of Alzheimer's and other neurodegenerative diseases.

Mutational analysis reveals the FUS homolog TAF15 as a candidate gene for familial amyotrophic lateral sclerosis

FUS, EWS, and TAF15 belong to the TET family of structurally similar DNA/RNA-binding proteins. Mutations in the FUS gene have recently been discovered as a cause of familial amyotrophic lateral sclerosis (FALS). Given the structural and functional similarities between the three genes, we screened TAF15 and EWS in 263 and 94 index FALS cases, respectively. No coding variants were found in EWS, while we identified six novel changes in TAF15. Of these, two 24 bp deletions and a R388H missense variant were also found in healthy controls. A D386N substitution was shown not to segregate with the disease in the affected pedigree. A single A31T and two R395Q changes were identified in FALS cases but not in over 1,100 controls. Interestingly, one of the R395Q FALS cases also harbors a TARDBP mutation (G384R). Altogether, these results suggest that additional studies are needed to determine whether mutations in the TAF15 gene represent a cause of FALS.

Genome-wide association studies: the key to unlocking neurodegeneration?

The successful discovery of genes that cause rare monogenic disorders has dominated our understanding of the genetic basis of neurodegenerative disease. The emergence of robust genome-wide association methodologies promises to explain the genetic etiology of the common sporadic forms of complex diseases. In addition to revealing the genetic susceptibility of neurodegenerative disease, genome-wide association studies (GWASs) should also be an unbiased generator of molecules that are relevant in disease pathogenesis. Despite this exciting potential, GWAS results have varied in their consistency and their ability to deliver these aims. The largest challenge that faces neuroscientists is the interpretation of the results of GWASs and the translation of the genetic findings into functional mechanisms that are biologically important in disease pathogenesis and, ultimately, treatment design. We examine recent results from GWASs of Alzheimer's disease and Parkinson's disease and explore their use and limitations. We further reflect on how these results may expedite progress in understanding and influencing the molecular pathogenesis of neurodegeneration.

Varietas: a functional variation database portal

Current high-throughput technologies for investigating genomic variation in large population based samples produce data on a scale of millions of variations. Browsing through these results and identifying relevant functional variations is a major hurdle in these genome-wide association studies. In order to help researchers locate the most promising associations, we have developed a web-based database portal called Varietas. Varietas can be used for retrieving information concerning genomic variations such as single-nucleotide polymorphisms (SNPs), copy number variants and insertions/deletions, while enabling users to annotate large number of variations in a batch like manner and to find information about related genes, phenotypes and diseases. Varietas also links out to various external genomic databases, allowing users to quickly browse through a set of variations and follow the most promising leads. Varietas periodically integrates data from the major SNP and genome databases, including Ensembl genome database, NCBI dbSNP database, The Genomic Association Database and SNPedia.

Database URL:http://kokki.uku.fi/bioinformatics/varietas/

Evaluation of 172 candidate polymorphisms for association with oligozoospermia or azoospermia in a large cohort of men of European descent

BACKGROUND

In spite of tremendous efforts by a number of groups, the search for single nucleotide polymorphisms (SNPs) strongly associated with male factor infertility by means of gene re-sequencing studies has yielded few likely candidates. A recent pilot, genome-wide SNP association study (GWAS) identified a list of SNPs associated with oligozoospermia and azoospermia. This is an expanded follow-up study of the SNPs identified by the GWAS as well as other SNPs from previously published gene re-sequencing studies.

METHODS

On the basis of the pilot GWAS and SNPs with published associations with male infertility, 172 SNPs were genotyped in men with idiopathic azoospermia or oligozoospermia using the Illumina BeadXpress platform.

RESULTS

Several SNPs were identified or confirmed to be significantly associated with oligozoospermia and/or azoospermia. More importantly, this follow-up study indicates that, at least in Caucasian men, no single common SNP accounts for a significant proportion of spermatogenic failure cases.

CONCLUSIONS

The associations reported in this study are promising, but much larger genome-wide studies will be necessary to confidently validate these SNPs and identify novel SNPs associated with male infertility.

Long non-coding RNAs in nervous system function and disease

Central nervous system (CNS) development, homeostasis, stress responses, and plasticity are all mediated by epigenetic mechanisms that modulate gene expression and promote selective deployment of functional gene networks in response to complex profiles of interoceptive and environmental signals. Thus, not surprisingly, disruptions of these epigenetic processes are implicated in the pathogenesis of a spectrum of neurological and psychiatric diseases. Epigenetic mechanisms involve chromatin remodeling by relatively generic complexes that catalyze DNA methylation and various types of histone modifications. There is increasing evidence that these complexes are directed to their sites of action by long non-protein-coding RNAs (lncRNAs), of which there are tens if not hundreds of thousands specified in the genome. LncRNAs are transcribed in complex intergenic, overlapping and antisense patterns relative to adjacent protein-coding genes, suggesting that many lncRNAs regulate the expression of these genes. LncRNAs also participate in a wide array of subcellular processes, including the formation and function of cellular organelles. Most lncRNAs are transcribed in a developmentally regulated and cell type specific manner, particularly in the CNS, wherein over half of all lncRNAs are expressed. While the numerous biological functions of lncRNAs are yet to be characterized fully, a number of recent studies suggest that lnRNAs are important for mediating cell identity. This function seems to be especially important for generating the enormous array of regional neuronal and glial cell subtypes that are present in the CNS. Further studies have also begun to elucidate additional roles played by lncRNAs in CNS processes, including homeostasis, stress responses and plasticity. Herein, we review emerging evidence that highlights the expression and function of lncRNAs in the CNS and suggests that lncRNA deregulation is an important factor in various CNS pathologies including neurodevelopmental, neurodegenerative and neuroimmunological disorders, primary brain tumors, and psychiatric diseases.

Genome-wide association studies: a powerful tool for neurogenomics

As their power and utility increase, genome-wide association (GWA) studies are poised to become an important element of the neurosurgeon's toolkit for diagnosing and treating disease. In this paper, the authors review recent findings and discuss issues associated with gathering and analyzing GWA data for the study of neurological diseases and disorders, including those of neurosurgical importance. Their goal is to provide neurosurgeons and other clinicians with a better understanding of the practical and theoretical issues associated with this line of research. A modern GWA study involves testing hundreds of thousands of genetic markers across an entire genome, often in thousands of individuals, for any significant association with a particular disease. The number of markers assayed in a study presents several practical and theoretical issues that must be considered when planning the study. Genome-wide association studies show great promise in our understanding of the genes underlying common neurological diseases and disorders, as well as in leading to a new generation of genetic tests for clinicians.

Measuring consequences of protein misfolding and cellular stress using OMICS techniques

The ambition to measure all or at least a significant fraction of relevant molecules in a cell culture or tissue sample has reached possible realization with the development of the so-called OMICS technologies. We will here briefly review current technologies and give examples of their applications in investigations related to protein misfolding diseases. We will primarily cover the classical OMICS categories GENOMICS, TRANSCRIPTOMICS, METABOLOMICS, and with some more detail PROTEOMICS. These techniques are in most cases performed by dedicated core facilities or commercial services. We will give an assessment of uses as well as limitations of these technologies supported by examples of their application in research related to protein misfolding. We will further briefly discuss genome-wide RNA interference and finally touch on bioinformatics, because the huge amounts of data typically collected with OMICS techniques requires the application of specific software to handle and stratify the data sets. Today, most biologists using OMICS-techniques must, at least in part, be able to analyze their own data using user-friendly web-based tools.

The era of genomic epidemiology

The recent revolution in genomics is already having a profound impact on the practice of epidemiology. The purpose of this commentary is to demonstrate how genomics and epidemiology will continue to rely heavily on each other, now and in the future, by illustrating a number of interaction points between these 2 disciplines: (1) the use of genomics to estimate disease heritability; (2) the impact of genomics on analytical study design; (3) how genome-wide data can be employed to effectively overcome residual population stratification arising from selection bias; (4) the importance of genomics as a tool in epidemiological investigation; (5) the importance of epidemiology in the collection of adequately phenotyped samples for genomics studies, and (6) for unraveling the clinical and therapeutic relevance of genetic variants once they are discovered.