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Elwyn R, Mitchell J, Kohn MR, Driver C, Hay P, Lagopoulos J, Hermens DF. Novel ketamine and zinc treatment for anorexia nervosa and the potential beneficial interactions with the gut microbiome. Neurosci Biobehav Rev 2023; 148:105122. [PMID: 36907256 DOI: 10.1016/j.neubiorev.2023.105122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 03/04/2023] [Accepted: 03/07/2023] [Indexed: 03/13/2023]
Abstract
Anorexia nervosa (AN) is a severe illness with diverse aetiological and maintaining contributors including neurobiological, metabolic, psychological, and social determining factors. In addition to nutritional recovery, multiple psychological and pharmacological therapies and brain-based stimulations have been explored; however, existing treatments have limited efficacy. This paper outlines a neurobiological model of glutamatergic and γ-aminobutyric acid (GABA)-ergic dysfunction, exacerbated by chronic gut microbiome dysbiosis and zinc depletion at a brain and gut level. The gut microbiome is established early in development, and early exposure to stress and adversity contribute to gut microbial disturbance in AN, early dysregulation to glutamatergic and GABAergic networks, interoceptive impairment, and inhibited caloric harvest from food (e.g., zinc malabsorption, competition for zinc ions between gut bacteria and host). Zinc is a key part of glutamatergic and GABAergic networks, and also affects leptin and gut microbial function; systems dysregulated in AN. Low doses of ketamine in conjunction with zinc, could provide an efficacious combination to act on NMDA receptors and normalise glutamatergic, GABAergic and gut function in AN.
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Affiliation(s)
- Rosiel Elwyn
- Thompson Institute, University of the Sunshine Coast, Birtinya, QLD, Australia; SouthWest Sydney Local Health District, Liverpool Hospital, Liverpool, NSW, Australia.
| | - Jules Mitchell
- Thompson Institute, University of the Sunshine Coast, Birtinya, QLD, Australia; SouthWest Sydney Local Health District, Liverpool Hospital, Liverpool, NSW, Australia
| | - Michael R Kohn
- AYA Medicine Westmead Hospital, CRASH (Centre for Research into Adolescent's Health) Western Sydney Local Health District, Sydney University, Australia; SouthWest Sydney Local Health District, Liverpool Hospital, Liverpool, NSW, Australia
| | - Christina Driver
- Thompson Institute, University of the Sunshine Coast, Birtinya, QLD, Australia; SouthWest Sydney Local Health District, Liverpool Hospital, Liverpool, NSW, Australia
| | - Phillipa Hay
- Translational Health Research Institute (THRI) School of Medicine, Western Sydney University, Campbelltown, NSW, Australia; SouthWest Sydney Local Health District, Liverpool Hospital, Liverpool, NSW, Australia
| | - Jim Lagopoulos
- Thompson Institute, University of the Sunshine Coast, Birtinya, QLD, Australia; SouthWest Sydney Local Health District, Liverpool Hospital, Liverpool, NSW, Australia
| | - Daniel F Hermens
- Thompson Institute, University of the Sunshine Coast, Birtinya, QLD, Australia; SouthWest Sydney Local Health District, Liverpool Hospital, Liverpool, NSW, Australia
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Possible association of CAG repeat polymorphism in KCNN3 encoding the potassium channel SK3 with oxaliplatin-induced neurotoxicity. Cancer Chemother Pharmacol 2018; 82:149-157. [PMID: 29774408 DOI: 10.1007/s00280-018-3600-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 05/09/2018] [Indexed: 12/15/2022]
Abstract
INTRODUCTION Data suggest a role of the potassium channel SK3 (KCNN3 gene) in oxaliplatin-induced neurotoxicity (OIN). Length variations in the polymorphic CAG repeat of the KCNN3 gene may be associated with the risk of OIN. MATERIALS AND METHODS We performed patch-clamp experiments on HEK293 cell lines, expressing SK3 channel isoforms with short (11) or long (24) CAG repetitions, to measure intracellular calcium concentrations to test the effects of oxaliplatin on current density. A retrospective study was carried out on patients with colorectal cancer who had received oxaliplatin-based chemotherapy. DNA for KCNN3 genotyping was extracted from leukocytes. The region containing the CAG repeats was amplified by PCR and the products separated by capillary electrophoresis for length analysis. The patients were divided into three groups depending on whether they carried two short alleles, one short allele and one long allele, or two long alleles. The primary endpoint was the onset of grade 2 or 3 neuropathy to oxaliplatin. RESULTS There was no difference in current density, but oxaliplatin induced a differential effect on apamin-sensitive current density between the two isoforms expressed in the HEK cell lines. There was a significant reduction of store-operated calcium entry into cells expressing the short and more active isoform only after high concentration of oxaliplatin exposition. Eighty-six patients were included in the clinical study. There was no significant association between OIN and KCNN3 polymorphism for the three groups. CONCLUSION We observed a slight association between OIN and CAG repeat polymorphisms of the KCNN3 gene in a preclinical model, but not a clinical study.
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Abstract
Over the past decade, considerable advances have been made in understanding genetic influences on eating pathology. Eating disorders aggregate in families, and twin studies reveal that additive genetic factors account for approximately 40% to 60% of liability to anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED). Molecular genetics studies have been undertaken to identify alterations in deoxyribonucleic acid sequence and/or gene expression that may be involved in the pathogenesis of disordered eating behaviors, symptoms, and related disorders and to uncover potential genetic variants that may contribute to variability of treatment response. This article provides an in-depth review of the scientific literature on the genetics of AN, BN, and BED including extant studies, emerging hypotheses, future directions, and clinical implications.
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Affiliation(s)
- Sara E Trace
- Department of Psychiatry, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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Brooks SJ, Rask-Andersen M, Benedict C, Schiöth HB. A debate on current eating disorder diagnoses in light of neurobiological findings: is it time for a spectrum model? BMC Psychiatry 2012; 12:76. [PMID: 22770364 PMCID: PMC3475111 DOI: 10.1186/1471-244x-12-76] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 05/14/2012] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Sixty percent of eating disorders do not meet criteria for anorexia- or bulimia nervosa, as defined by the Diagnostic and Statistical Manual version 4 (DSM-IV). Instead they are diagnosed as 'eating disorders not otherwise specified' (EDNOS). Discrepancies between criteria and clinical reality currently hampering eating disorder diagnoses in the DSM-IV will be addressed by the forthcoming DSM-V. However, future diagnoses for eating disorders will rely on current advances in the fields of neuroimaging and genetics for classification of symptoms that will ultimately improve treatment. DISCUSSION Here we debate the classification issues, and discuss how brain imaging and genetic discoveries might be interwoven into a model of eating disorders to provide better classification and treatment. The debate concerns: a) current issues in the classification of eating disorders in the DSM-IV, b) changes proposed for DSM-V, c) neuroimaging eating disorder research and d) genetic eating disorder research. SUMMARY We outline a novel evidence-based 'impulse control' spectrum model of eating disorders. A model of eating disorders is proposed that will aid future diagnosis of symptoms, coinciding with contemporary suggestions by clinicians and the proposed changes due to be published in the DSM-V.
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Affiliation(s)
| | | | - Christian Benedict
- Department of Neuroscience, University of Uppsala, Box 593, Uppsala, Sweden
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Wang K, Zhang H, Bloss CS, Duvvuri V, Kaye W, Schork NJ, Berrettini W, Hakonarson H. A genome-wide association study on common SNPs and rare CNVs in anorexia nervosa. Mol Psychiatry 2011; 16:949-59. [PMID: 21079607 DOI: 10.1038/mp.2010.107] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Anorexia nervosa (AN) is a mental illness with high mortality that most commonly afflicts adolescent female individuals. Clinical symptoms include chronic food refusal, weight loss and body image distortions. We carried out a genome-wide association study on 1033 AN cases and 3733 pediatric control subjects, all of whom were of European ancestry and were genotyped on the Illumina HumanHap610 platform (Illumina, San Diego, CA, USA). We confirmed that common single-nucleotide polymorphisms (SNPs) within OPRD1 (rs533123, P=0.0015) confer risk for AN, and obtained suggestive evidence that common SNPs near HTR1D (rs7532266, P=0.04) confer risk for restricting-type AN specifically. However, no SNPs reached genome-wide significance in our data, whereas top association signals were detected near ZNF804B, CSRP2BP, NTNG1, AKAP6 and CDH9. In parallel, we performed genome-wide analysis on copy number variations (CNVs) using the signal intensity data from the SNP arrays. We did not find evidence that AN cases have more CNVs than control subjects, nor do they have over-representation of rare or large CNVs. However, we identified several regions with rare CNVs that were only observed in AN cases, including a recurrent 13q12 deletion (1.5 Mb) disrupting SCAS in two cases, and CNVs disrupting the CNTN6/CNTN4 region in several AN cases. In conclusion, our study suggests that both common SNPs and rare CNVs may confer genetic risk to AN. These results point to intriguing genes that await further validation in independent cohorts for confirmatory roles in AN.
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Affiliation(s)
- K Wang
- Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, PA, USA
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Root TL, Szatkiewicz JP, Jonassaint CR, Thornton LM, Pinheiro AP, Strober M, Bloss C, Berrettini W, Schork NJ, Kaye WH, Bergen AW, Magistretti P, Brandt H, Crawford S, Crow S, Fichter MM, Goldman D, Halmi KA, Johnson C, Kaplan AS, Keel PK, Klump KL, La Via M, Mitchell JE, Rotondo A, Treasure J, Woodside DB, Bulik CM. Association of candidate genes with phenotypic traits relevant to anorexia nervosa. EUROPEAN EATING DISORDERS REVIEW 2011; 19:487-93. [PMID: 21780254 DOI: 10.1002/erv.1138] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Revised: 05/06/2011] [Accepted: 05/15/2011] [Indexed: 11/09/2022]
Abstract
This analysis is a follow-up to an earlier investigation of 182 genes selected as likely candidate genetic variations conferring susceptibility to anorexia nervosa (AN). As those initial case-control results revealed no statistically significant differences in single nucleotide polymorphisms, herein, we investigate alternative phenotypes associated with AN. In 1762 females, using regression analyses, we examined the following: (i) lowest illness-related attained body mass index; (ii) age at menarche; (iii) drive for thinness; (iv) body dissatisfaction; (v) trait anxiety; (vi) concern over mistakes; and (vii) the anticipatory worry and pessimism versus uninhibited optimism subscale of the harm avoidance scale. After controlling for multiple comparisons, no statistically significant results emerged. Although results must be viewed in the context of limitations of statistical power, the approach illustrates a means of potentially identifying genetic variants conferring susceptibility to AN because less complex phenotypes associated with AN are more proximal to the genotype and may be influenced by fewer genes.
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Affiliation(s)
- Tammy L Root
- Johns Hopkins University School of Medicine, Division of General Internal Medicine, Baltimore, MD, USA
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Monteleone P, Maj M. The Role of Gene Polymorphisms in Susceptibility to Anorexia Nervosa and Bulimia Nervosa. HANDBOOK OF BEHAVIOR, FOOD AND NUTRITION 2011:1175-1200. [DOI: 10.1007/978-0-387-92271-3_76] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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Abstract
The eating disorders anorexia nervosa (AN), bulimia nervosa (BN), binge eating disorder and allied diagnoses such as eating disorder not otherwise specified are common, complex psychiatric disorders with a significant genetic component. Aetiology is unknown, but both phenotypic characteristics and genetic factors appear to be shared across these disorders, and indeed patients often change between diagnostic categories. Molecular studies have attempted to define genetic risk factors for these disorders, including case-control and family-based candidate gene association studies and linkage analysis of multiply affected nuclear families. These have used both clinical diagnoses and eating disorder-related intermediate phenotypes such as drive-for-thinness or body dissatisfaction. Candidate gene studies have focussed on neurotransmitter and neurodevelopmental systems [e.g. serotonergic, opioid, cannabinoid and dopaminergic receptors, and brain-derived neurotrophic factor (BDNF)], appetite regulatory peptides and their receptors [leptin, ghrelin, agouti-related protein (AgRP), melanocortin receptors, neuropeptide Y], energy balance systems (e.g. uncoupling proteins), genes implicated in obesity (e.g. FTO) and sex hormone systems (e.g. oestrogen receptors), either identified on the basis of their function alone or as positional candidates from linkage analysis. Of these studies, linkage analysis implicates 1p33-36 for AN, 1q31.3 for quantitative behavioural traits related to anorexia and 10p14 for BN, as well as other behavioural phenotypes across both disorders. Candidate gene association has implicated BDNF, delta 1 opioid receptor (OPDR1) and AgRP. More recently, with the advent of genome-wide association studies (GWAS), analysis with microsatellite markers has implicated novel candidate loci for AN at 1q41 and 11q22, and further GWAS results are expected in the near future.
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Affiliation(s)
- Sietske G Helder
- MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, Denmark Hill, London, SE5 8AF, UK.
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Pinheiro AP, Bulik CM, Thornton LM, Sullivan PF, Root TL, Bloss CS, Berrettini WH, Schork NJ, Kaye WH, Bergen AW, Magistretti P, Brandt H, Crawford S, Crow S, Fichter MM, Goldman D, Halmi KA, Johnson C, Kaplan AS, Keel PK, Klump KL, La Via M, Mitchell JE, Strober M, Rotondo A, Treasure J, Woodside DB. Association study of 182 candidate genes in anorexia nervosa. Am J Med Genet B Neuropsychiatr Genet 2010; 153B:1070-80. [PMID: 20468064 PMCID: PMC2963154 DOI: 10.1002/ajmg.b.31082] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
We performed association studies with 5,151 SNPs that were judged as likely candidate genetic variations conferring susceptibility to anorexia nervosa (AN) based on location under reported linkage peaks, previous results in the literature (182 candidate genes), brain expression, biological plausibility, and estrogen responsivity. We employed a case-control design that tested each SNP individually as well as haplotypes derived from these SNPs in 1,085 case individuals with AN diagnoses and 677 control individuals. We also performed separate association analyses using three increasingly restrictive case definitions for AN: all individuals with any subtype of AN (All AN: n = 1,085); individuals with AN with no binge eating behavior (AN with No Binge Eating: n = 687); and individuals with the restricting subtype of AN (Restricting AN: n = 421). After accounting for multiple comparisons, there were no statistically significant associations for any individual SNP or haplotype block with any definition of illness. These results underscore the importance of large samples to yield appropriate power to detect genotypic differences in individuals with AN and also motivate complementary approaches involving Genome-Wide Association (GWA) studies, Copy Number Variation (CNV) analyses, sequencing-based rare variant discovery assays, and pathway-based analysis in order to make up for deficiencies in traditional candidate gene approaches to AN.
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Affiliation(s)
- Andrea Poyastro Pinheiro
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Cynthia M. Bulik
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina,Correspondence to: Dr. Cynthia M. Bulik, Ph.D., Department of Psychiatry, University of North Carolina at Chapel Hill, 101 Manning Drive, CB #7160, Chapel Hill, NC 27599 -7160.
| | - Laura M. Thornton
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Patrick F. Sullivan
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Tammy L. Root
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Cinnamon S. Bloss
- Scripps Genomic Medicine, The Scripps Research Institute, La Jolla, California
| | - Wade H. Berrettini
- Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Nicholas J. Schork
- Scripps Genomic Medicine, The Scripps Research Institute, La Jolla, California
| | - Walter H. Kaye
- Department of Psychiatry, University of California at San Diego, San Diego, California,Correspondence to: Dr. Walter H. Kaye, M.D., Department of Psychiatry, University of California San Diego, 8950 Villa La Jolla Dr., Suite C207, La Jolla, CA 92037.
| | - Andrew W. Bergen
- Center for Health Sciences, SRI International, Menlo Park, California
| | - Pierre Magistretti
- Department of Psychiatry, Brain Mind Institute EPFL—Lausanne, Center for Psychiatric Neuroscience, University of Lausanne Medical School, Lausanne, Switzerland
| | - Harry Brandt
- Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland
| | - Steve Crawford
- Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland
| | - Scott Crow
- Department of Psychiatry, University of Minnesota, Minneapolis, Minnesota
| | - Manfred M. Fichter
- Roseneck Hospital for Behavioral Medicine, Prien, Germany, Department of Psychiatry, University of Munich (LMU), Munich, Germany
| | - David Goldman
- Laboratory of Neurogenetics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland
| | - Katherine A. Halmi
- New York Presbyterian Hospital, Westchester Division, Weill Medical College of Cornell University, White Plains, New York
| | - Craig Johnson
- Laureate Psychiatric Clinic and Hospital, Tulsa, Oklahoma
| | - Allan S. Kaplan
- Center for Addiction and Mental Health, Toronto, Canada, Department of Psychiatry, Toronto General Hospital, University Health Network, Toronto, Canada
| | - Pamela K. Keel
- Department of Psychology, Florida State University, Tallahassee, Florida
| | - Kelly L. Klump
- Department of Psychology, Michigan State University, East Lansing, Michigan
| | - Maria La Via
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - James E. Mitchell
- Neuropsychiatric Research Institute, Fargo, North Dakota, Department of Clinical Neuroscience, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota
| | - Michael Strober
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California
| | - Alessandro Rotondo
- Neuropsychiatric Research Biotechnologies, University of Pisa, Pisa, Italy
| | - Janet Treasure
- Eating Disorders Section, Institute of Psychiatry, King’s College, University of London, London, England
| | - D. Blake Woodside
- Center for Addiction and Mental Health, Toronto, Canada, Department of Psychiatry, Toronto General Hospital, University Health Network, Toronto, Canada, Department of Psychiatry, University of Toronto, Toronto, Canada
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López Herráez D, Bauchet M, Tang K, Theunert C, Pugach I, Li J, Nandineni MR, Gross A, Scholz M, Stoneking M. Genetic variation and recent positive selection in worldwide human populations: evidence from nearly 1 million SNPs. PLoS One 2009; 4:e7888. [PMID: 19924308 PMCID: PMC2775638 DOI: 10.1371/journal.pone.0007888] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2009] [Accepted: 10/20/2009] [Indexed: 01/21/2023] Open
Abstract
Background Genome-wide scans of hundreds of thousands of single-nucleotide polymorphisms (SNPs) have resulted in the identification of new susceptibility variants to common diseases and are providing new insights into the genetic structure and relationships of human populations. Moreover, genome-wide data can be used to search for signals of recent positive selection, thereby providing new insights into the genetic adaptations that occurred as modern humans spread out of Africa and around the world. Methodology We genotyped approximately 500,000 SNPs in 255 individuals (5 individuals from each of 51 worldwide populations) from the Human Genome Diversity Panel (HGDP-CEPH). When merged with non-overlapping SNPs typed previously in 250 of these same individuals, the resulting data consist of over 950,000 SNPs. We then analyzed the genetic relationships and ancestry of individuals without assigning them to populations, and we also identified candidate regions of recent positive selection at both the population and regional (continental) level. Conclusions Our analyses both confirm and extend previous studies; in particular, we highlight the impact of various dispersals, and the role of substructure in Africa, on human genetic diversity. We also identified several novel candidate regions for recent positive selection, and a gene ontology (GO) analysis identified several GO groups that were significantly enriched for such candidate genes, including immunity and defense related genes, sensory perception genes, membrane proteins, signal receptors, lipid binding/metabolism genes, and genes involved in the nervous system. Among the novel candidate genes identified are two genes involved in the thyroid hormone pathway that show signals of selection in African Pygmies that may be related to their short stature.
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Affiliation(s)
| | - Marc Bauchet
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Kun Tang
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | | | - Irina Pugach
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Jing Li
- National Drug Screening Laboratory, China Pharmaceutical University, Nanjing City, China
| | - Madhusudan R. Nandineni
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Laboratory of DNA Fingerprinting, Centre for DNA Fingerprinting and Diagnostics, Nampally, Hyderabad, India
| | - Arnd Gross
- Institute for Medical Informatics, Statistics and Epidemiology, University of Leipzig, Leipzig, Germany
| | - Markus Scholz
- Institute for Medical Informatics, Statistics and Epidemiology, University of Leipzig, Leipzig, Germany
| | - Mark Stoneking
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- * E-mail:
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Molecular mechanisms underlying anorexia nervosa: focus on human gene association studies and systems controlling food intake. ACTA ACUST UNITED AC 2009; 62:147-64. [PMID: 19931559 DOI: 10.1016/j.brainresrev.2009.10.007] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 10/08/2009] [Accepted: 10/08/2009] [Indexed: 01/08/2023]
Abstract
Anorexia nervosa (AN) is a complex multi-factorial disease with high heritability. The psychological AN symptoms are poorly connected with specific molecular mechanisms. Here we review the molecular basis of AN with the focus on human genetic association studies; we put these in the experimental biological context with emphasis on molecular systems controlling food intake and body weight in a direct or indirect manner. We systematically searched for human genetic studies related to AN and grouped data into main categories/systems reflecting their major known roles: (1) Systems related to mental disorders (serotonin, brain-derived neurotrophic factor (BDNF), norepinephrine (NE), glutamate (NMDA) receptor and SK3 channel, KCCN3). (2) Hunger regulatory systems (leptin, AGRP, MSH, melanocortin 4 receptor (MC4R), NPY, ghrelin, cholecystokinin (CCK). (3) Feeding motivation- and reward-related systems (opioids, OPRD1, cannabinoids (anandamide (AEA), THC, CBR1), dopamine, DRD2, DRD3, DRD4, catecholamine-O-methyl transferase (COMT). (4) Systems regulating energy metabolism (uncoupling proteins 2 and 3 (UCP2 and UCP3). (5) Neuroendocrine systems with emphasis on sex hormones (estrogen receptor-beta (ESR2). (6) The immune system and inflammatory response (tumor necrosis factor-alpha (TNF-alpha)). Overall, we found that in total 175 association studies have been performed on AN cohorts on 128 different polymorphisms related to 43 genes. We review the strongest associations, identify some genes that have an important role in regulating BMI whose possible relationship to AN has not been investigated and discuss the potential targets for pharmacological interventions.
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Molecular and cellular basis of small--and intermediate-conductance, calcium-activated potassium channel function in the brain. Cell Mol Life Sci 2008; 65:3196-217. [PMID: 18597044 PMCID: PMC2798969 DOI: 10.1007/s00018-008-8216-x] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Small conductance calcium-activated potassium (SK or KCa2) channels link intracellular calcium transients to membrane potential changes. SK channel subtypes present different pharmacology and distribution in the nervous system. The selective blocker apamin, SK enhancers and mice lacking specific SK channel subunits have revealed multifaceted functions of these channels in neurons, glia and cerebral blood vessels. SK channels regulate neuronal firing by contributing to the afterhyperpolarization following action potentials and mediating IAHP, and partake in a calcium-mediated feedback loop with NMDA receptors, controlling the threshold for induction of hippocampal long-term potentiation. The function of distinct SK channel subtypes in different neurons often results from their specific coupling to different calcium sources. The prominent role of SK channels in the modulation of excitability and synaptic function of limbic, dopaminergic and cerebellar neurons hints at their possible involvement in neuronal dysfunction, either as part of the causal mechanism or as potential therapeutic targets.
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Monteleone P, Maj M. Genetic susceptibility to eating disorders: associated polymorphisms and pharmacogenetic suggestions. Pharmacogenomics 2008; 9:1487-520. [DOI: 10.2217/14622416.9.10.1487] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Anorexia nervosa (AN), bulimia nervosa (BN) and binge-eating disorder (BED) are characterized by abnormal eating behaviors often resulting in dramatic physical consequences for the patients. The etiology of eating disorders (EDs) is currently unknown; however, a strong genetic contribution is likely to be involved. To date, the majority of genetic studies have focused on candidate genes, and polymorphic variants of genes coding for substances likely to be involved in the etiopathogenesis of EDs have been assessed for association with AN, BN, BED and/or ED-related phenotypic traits. Results have been generally inconsistent and cannot be considered conclusive because of several methodological flaws and differences, such as small sample sizes, ethnic heterogeneity of studied populations, lack of statistical correction for multiple testing, adoption of different diagnostic criteria and population stratification. Although, at present, no convincing evidence for associations of candidate genes with EDs has been provided, the 5-HT2A receptor gene and the BDNF gene seem to be promising candidates for genetic influences on AN, since polymorphic variants of these genes have been found quite consistently, although not specifically, linked to AN restricting subtype in large sample studies. Moreover, pharmacogenetic investigations have suggested a possible role of some gene polymorphisms in predicting the response to treatment with selective serotonin reuptake inhibitors in BN, but results are still preliminary. The heterogeneity of ED phenotypes is believed to represent the most relevant variable responsible for contradictory and not conclusive results. Future studies should focus on more homogeneous subgroups, either relying on specific ED traits or identifying endophenotypes. This will be useful also for prevention and treatment of EDs.
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Affiliation(s)
- Palmiero Monteleone
- Department of Psychiatry, University of Naples SUN, Largo Madonna delle Grazie, 80138 Naples, Italy
| | - Mario Maj
- Department of Psychiatry, University of Naples SUN, Largo Madonna delle Grazie, 80138 Naples, Italy
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Butland SL, Devon RS, Huang Y, Mead CL, Meynert AM, Neal SJ, Lee SS, Wilkinson A, Yang GS, Yuen MMS, Hayden MR, Holt RA, Leavitt BR, Ouellette BFF. CAG-encoded polyglutamine length polymorphism in the human genome. BMC Genomics 2007; 8:126. [PMID: 17519034 PMCID: PMC1896166 DOI: 10.1186/1471-2164-8-126] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Accepted: 05/22/2007] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Expansion of polyglutamine-encoding CAG trinucleotide repeats has been identified as the pathogenic mutation in nine different genes associated with neurodegenerative disorders. The majority of individuals clinically diagnosed with spinocerebellar ataxia do not have mutations within known disease genes, and it is likely that additional ataxias or Huntington disease-like disorders will be found to be caused by this common mutational mechanism. We set out to determine the length distributions of CAG-polyglutamine tracts for the entire human genome in a set of healthy individuals in order to characterize the nature of polyglutamine repeat length variation across the human genome, to establish the background against which pathogenic repeat expansions can be detected, and to prioritize candidate genes for repeat expansion disorders.
Results
We found that repeats, including those in known disease genes, have unique distributions of glutamine tract lengths, as measured by fragment analysis of PCR-amplified repeat regions. This emphasizes the need to characterize each distribution and avoid making generalizations between loci. The best predictors of known disease genes were occurrence of a long CAG-tract uninterrupted by CAA codons in their reference genome sequence, and high glutamine tract length variance in the normal population. We used these parameters to identify eight priority candidate genes for polyglutamine expansion disorders. Twelve CAG-polyglutamine repeats were invariant and these can likely be excluded as candidates. We outline some confusion in the literature about this type of data, difficulties in comparing such data between publications, and its application to studies of disease prevalence in different populations. Analysis of Gene Ontology-based functions of CAG-polyglutamine-containing genes provided a visual framework for interpretation of these genes' functions. All nine known disease genes were involved in DNA-dependent regulation of transcription or in neurogenesis, as were all of the well-characterized priority candidate genes.
Conclusion
This publication makes freely available the normal distributions of CAG-polyglutamine repeats in the human genome. Using these background distributions, against which pathogenic expansions can be identified, we have begun screening for mutations in individuals clinically diagnosed with novel forms of spinocerebellar ataxia or Huntington disease-like disorders who do not have identified mutations within the known disease-associated genes.
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Gargus JJ. Ion channel functional candidate genes in multigenic neuropsychiatric disease. Biol Psychiatry 2006; 60:177-85. [PMID: 16497276 DOI: 10.1016/j.biopsych.2005.12.008] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2005] [Revised: 11/15/2005] [Accepted: 12/15/2005] [Indexed: 10/25/2022]
Abstract
Scores of monogenic Mendelian ion channel diseases serve to anchor the pathophysiology of the channelopathies, but there are also now clear examples of environmental, pharmacogenetic, and acquired channelopathy mechanisms. The cardinal feature of heritable ion channel disease is a periodic disturbance of rhythmic function in constitutionally hyperexcitable tissue. While the complexity of neuroanatomy obscures functional analysis of mutations causing monogenic seizure, ataxia, or migraine syndromes, extrapolation from the cardiac (Long QT [LQT]) and muscle (Periodic Paralysis) channelopathy syndromes provides a simplified predictive framework of molecular pathology: electrically stabilizing potassium ion (K(+)) and chloride ion (Cl(-)) channels, likely having lesions that diminish their current, and excitatory Na(+) channels, likely having gain-of-function lesions. The voltage-gated calcium channel gene family that contains CACNA1C, the newest LQT locus, causing Timothy Syndrome with a phenotype including autism, has proven to be particularly informative for its members' ability to tie the various central nervous system (CNS) phenotypes together in an interpretable fashion, now including direct extension to the classically multigenic neuropsychiatric phenotypes. Features of a promising ion channel candidate gene arise from its broad locus, gene family, nature of alleles, physiology and pharmacology, tissue expression profile, and phenotype in model organisms. KCNN3 is explored as a paradigm to consider.
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Affiliation(s)
- J Jay Gargus
- Department of Physiology, Section of Human Genetics, University of California, Irvine, California 92697-4034, USA.
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