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Research Technology / Nucleic Acid / Genome-wide Association Study

Exome Sequencing on Malignant Meningiomas Identified Mutations in Neurofibromatosis Type 2 (NF2) and Meningioma 1 (MN1) Genes

Abstract: Background: Meningiomas are tumors originating from the membranous layers surrounding the central nervous system, and are generally regarded as "benign" tumors of the brain. Malignant meningiomas are rare and are typically associated with a higher risk of local tumor recurrence and a poorer prognosis (median survival time <2 years). Previous genome-wide association studies and exome sequencing studies have identified genes that play a role in susceptibility to meningiomas, but these studies did not focus specifically on malignant tumors. Methods: We performed exome sequencing on five malignant meningiomas on the Illumina HiSeq2000 platform using Agilent SureSelect Human All Exon kits. We used wANNOVAR web server to annotate and prioritize variants, identified candidate genes with recurrent mutations, and validated selected mutations by Sanger sequencing. We next designed custom NimbleGen targeted region arrays on five candidate genes, and sequenced four additional malignant meningiomas. Results: From exome sequencing data, we identified several frequently mutated genes including NF2, MN1, ARID1B, SEMA4D, and MUC2, with private mutations in tumors. We sequenced these genes in four additional samples and identified potential driver mutations in NF2 (neurofibromatosis type 2) and MN1 (meningioma 1). Conclusions: We confirmed that mutations in NF2 may play a role in progression of meningiomas, and nominated MN1 as a candidate gene for malignant transformation of meningiomas. Our sample size is limited by the extreme rarity of malignant meningiomas, but our study represents one of the first sequencing studies focusing on the malignant subtype. ... Read more

Pharmacogenomics in Childhood Rheumatic Disorders: A Foundation for Future Individualized Therapy

Abstract: Investigating the effect of genotype on drug response in children is an evolving field, with many challenges, but there is great potential to optimize safe and effective use of drugs in children. An exponential increase in available medications for use in children with rheumatic disease has opened seemingly endless genotype/phenotype relationships to explore, but challenges inherent in studying rare diseases and the often overlooked role of ontogeny contribute to limitations in pharmacogenomic studies in this population. With careful recognition of the importance of development, improved phenotyping with the incorporation of biomarkers, and expanding collaborative efforts on a national and even international scale, the field of pediatric rheumatology has the opportunity to strategically study the new therapeutic armamentarium available and provide individualized safe and effective therapies to our population of patients. ... Read more

Integration of Genomics into Medical Practice

Abstract: Although some have wondered whether the sequencing of the human genome has led to major advances in medicine, in fact there are multiple examples where genomics has been integrated into medical practice. In the area of prevention, genomic approaches are now used for non-invasive prenatal testing of fetal DNA in the maternal circulation, for expanded preconceptional screening for carrier status, for autosomal recessive disorders, and for assessment of risk of common disease. In the area of diagnosis, major advances have been made in cytogenomics and in use of whole exome or whole genome sequencing. In therapeutics, pharmacogenetic testing is now feasible, tumor genome sequencing is being used to guide cancer therapy, and genomic discoveries are enabling development of new targeted therapies. Ultimately it is possible that genome sequencing may be done for all individuals on a routine basis, though there remain significant technical, ethical, and medical systems challenges to be overcome. It is likely that integration of genomics into medical practice will occur gradually over a long period of time, but the process is now well underway. ... Read more

Pharmacogenetics of Antidepressants, Mood Stabilizers, and Antipsychotics in Diverse Human Populations

Abstract: An increasing focus on personalized medicine is driving a renewed effort to understand the impact of ethnic and genetic background on treatment outcomes. Since responses to psychopharmacological treatments continue to be sub-optimal, there is a pressing need to identify markers of tolerability and efficacy. Pharmacogenomic studies aim to find such markers within the human genome, and have made some progress in recent years. Progress has been slower in populations with diverse racial and ethnic backgrounds. Here we review 10 genome-wide association studies (GWAS) that assessed outcomes after antidepressant, antipsychotic, or mood stabilizer treatment. These studies used samples collected by the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE), Sequenced Treatment Alternatives to Relieve Depression (STAR*D), and Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD) studies. We highlight findings from African American and European American participants since they are the largest groups studied, but we also address issues related to Asian and Hispanic groups. None of the GWAS we reviewed identified individual genetic markers at genome-wide significance, probably due to limited sample sizes. However, all the studies found poorer outcomes among African American participants. Some of this disparity seems to be explained by psychosocial and economic disadvantages, but at least 2 studies found that widespread genetic differences between participants of European and African ancestry also play an important role. Non-European groups are underrepresented in these studies, but the differences that are evident so far suggest that poorer outcomes among African Americans are not inevitable and may be particularly suited to pharmacogenomic strategies. The vision of more personalized psychopharmacology may critically depend on larger studies in more diverse human populations. ... Read more

Statin Pharmacogenomics: Pursuing Biomarkers for Predicting Clinical Outcomes

Abstract: Indicated for treating hyperlipidemias and for the prevention of cardiovascular disease (CVD), statins rank among the most commonly prescribed drug classes. While statins are considered to be highly effective in preventing atherosclerotic events, a substantial portion of treated patients still progress to overt CVD. Genetic factors are thought to contribute substantially to treatment outcome. Several candidate genes have been associated with statin dose requirements and treatment outcomes, but a clinically relevant pharmacogenomics test to guide statin therapy has not yet emerged. Here we define basic pharmacogenomics terminology, present strong candidate genes (CETP, HMGCR, SLCO1B1, ABCB1, and CYP3A4/5), and discuss the challenges in developing much-needed statin pharmacogenomics biomarkers for predicting treatment outcomes. ... Read more

Genetic Susceptibility to Primary Angle Closure Glaucoma (PACG)

Abstract: Glaucoma is a group of heterogeneous optic neuropathy and is the second leading cause of irreversible blindness worldwide. The two most common clinical types of glaucoma include primary open-angle (POAG) and primary angle-closure glaucoma (PACG). PACG is characterized by the closure of angles between iris and trabecular meshwork (iridocorneal angles) mainly because of anatomic abnormalities. The condition is more prevalent in Chinese, Asian Indians, and Eskimos. Because of an unusually high incidence of PACG among siblings of affected patients, it was suggested that genetic factors were involved in its pathology and the action of a large number of grouped or independently inherited genes along with environmental factors result in anatomical abnormalities of PACG. In PACG, the genetic basis is not well understood. Genome-wide association studies have identified several candidate genes in relation to PACG in several different populations. However, they are not reproduced from population to population or the results are controversial. This may indicate that the involvement of genetic abnormality in the pathogenesis of PACG is complex. The availability of spontaneously occurring large animal models such as dogs may provide an opportunity to identify genes responsible for the pathophysiology of PACG in the future. This article summarizes the current status of genetic investigations on PACG which is the most common cause of blindness worldwide. ... Read more

Network Medicine Approaches to the Genetics of Complex Diseases

Abstract: Complex diseases are caused by perturbations of biological networks. Genetic analysis approaches focused on individual genetic determinants are unlikely to characterize the network architecture of complex diseases comprehensively. Network medicine, which applies systems biology and network science to complex molecular networks underlying human disease, focuses on identifying the interacting genes and proteins which lead to disease pathogenesis. The long biological path between a genetic risk variant and development of a complex disease involves a range of biochemical intermediates, including coding and non-coding RNA, proteins, and metabolites. Transcriptomics, proteomics, metabolomics, and other -omics technologies have the potential to provide insights into complex disease pathogenesis, especially if they are applied within a network biology framework. Most previous efforts to relate genetics to -omics data have focused on a single -omics platform; the next generation of complex disease genetics studies will require integration of multiple types of -omics data sets in a network context. Network medicine may also provide insight into complex disease heterogeneity, serve as the basis for new disease classifications that reflect underlying disease pathogenesis, and guide rational therapeutic and preventive strategies. ... Read more

Recent Advances in Non-small Cell Lung Cancer Biology and Clinical Management

Abstract: Despite advances in surgery, chemotherapy, and radiotherapy over the last decades, the death rate from lung cancer has remained largely unchanged, which is mainly due to metastatic disease. Because of the overall poor prognosis, new treatment strategies for lung cancer patients are urgently needed. In this review, we summarize recent advances in non-small cell lung cancer (NSCLC) screening and diagnostic workup. We discuss current clinical management, highlighting stage-specific therapy approaches, chemotherapy options for advanced-stage patients, along with new agents such as vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR) monoclonal antibodies, and the EGFR-targeting tyrosine kinase inhibitors erlotinib and gefitinib, and the anaplastic lymphoma kinase (ALK) inhibitor crizotinib. Finally, we give an outlook into NSCLC disease biology, focusing on the importance of EGFR activating mutations and the role of the tumor-microenvironment. CXCR4 chemokine receptors expressed on NSCLC cells are a central pathway of NSCLC cross talk with the tumor microenvironment, as they induce activation, migration, and tumor cell adhesion to stromal cells, which in turn provides growth- and drug resistance-signals. Because of the growing evidence that the microenvironment in NSCLC promotes disease progression, we expect that selected molecular pathways of cross talk between NSCLC cells and their microenvironment will become alternative therapeutic targets in the near future. ... Read more

miRNAs at the Crossroad Between Hematopoietic Malignancies and Autoimmune Pathogenesis

Abstract: The study of microRNA (miRNA) regulation in the pathogenesis of autoimmune diseases and hematopoietic malignancies provides new understanding of the mechanisms of disease and is currently the focus of many researchers in the field. Autoimmune disorders and cancers of immune system comprise a wide range of genetically complex diseases that share certain aspects of dysregulated genetic networks, most notably deactivation of apoptosis. miRNA mechanisms control gene expression at the post-transcriptional level, linking mRNA processing and gene function. Considerable amount of data have been accumulated that indicate that the alteration of miRNA expression closely mirrors the development of immune system diseases and is likely to play a role in their pathogenesis. However, a knowledge gap remains in our understanding of how miRNA dysregulation and the specific effects of miRNAs on target gene expression underlay the disease phenotype. Here we review a number of studies describing miRNA alterations in autoimmune diseases and hematopoietic cancers and discuss potential miRNA-regulated mechanisms that differentially influence the development of autoimmunity as compared to cancer progression. ... Read more

BRCA and Beyond: A Genome-first Approach to Familial Breast Cancer Risk Assessment

Abstract: Breast cancer affects around 12% of women in the Western world, but individual lifetime risks vary significantly within any population. Currently, familial cancer services assess and manage familial breast cancer risk based on the presence of a family history of the condition or the identification of high-risk breast cancer susceptibility alleles. This model of clinical care provides an accurate genetic risk assessment for only the minority of families referred to these services. With increasing access to technologies that interrogate human variation at the genome-wide level, it is envisaged that familial breast cancer risk assessments will in the future assume a genome-first approach. This review discusses and highlights the different components of familial breast cancer risk, which will need to be integrated to make this new model of clinical risk assessment possible. ... Read more

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