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Genetic variants in YWHAZ contribute to psychiatric disorders such as autism spectrum disorder and schizophrenia, and have been related to an impaired neurodevelopment in humans and mice. Here, we have used zebrafish to investigate the mechanisms by which YWHAZ contributes to neurodevelopmental disorders. We observed that ywhaz expression was pan-neuronal during developmental stages and restricted to Purkinje cells in the adult cerebellum, cells that are described to be reduced in number and size in autistic patients. We then performed whole-brain imaging in wild-type and ywhaz CRISPR/Cas9 knockout (KO) larvae and found altered neuronal activity and connectivity in the hindbrain. Adult ywhaz KO fish display decreased levels of monoamines in the hindbrain and freeze when exposed to novel stimuli, a phenotype that can be reversed with drugs that target monoamine neurotransmission. These findings suggest an important role for ywhaz in establishing neuronal connectivity during development and modulating both neurotransmission and behaviour in adults.

Drug addiction, one of the major health problems worldwide, is characterized by the loss of control in drug intake, craving, and withdrawal. At the individual level, drugs of abuse produce serious consequences on health and have a negative impact on the family environment and on interpersonal and work relationships. At a wider scale, they have significant socio-economic and public health consequences and they cause delinquency and citizen insecurity. Cocaine, a psychostimulant substance, is one of the most used illicit drugs, especially in America, Western Europe, and Australia. Cocaine use disorders (CUD) are complex multifactorial conditions driven by both genetic and environmental influences. Importantly, not all people who use cocaine develop CUD, and this is due, at least in part, to biological factors that are encoded in the genome of individuals. Acute and repeated use of cocaine induces epigenetic and gene expression changes responsible for the neuronal adaptations and the remodeling of brain circuits that lead to the transition from use to abuse or dependence. The purpose of this review is to delineate such factors, which should eventually help to understand the inter-individual variability in the susceptibility to cocaine addiction. Heritability estimates for CUD are high and genetic risk factors for cocaine addiction have been investigated by candidate gene association studies (CGAS) and genome-wide association studies (GWAS), reviewed here. Also, the high comorbidity that exists between CUD and several other psychiatric disorders is well known and includes phenotypes like schizophrenia, aggression, antisocial or risk-taking behaviors. Such comorbidities are associated with a worse lifetime trajectory, and here we report shared genetic factors that may contribute to them. Gene expression changes and epigenetic modifications induced by cocaine use and chronic abuse in humans are addressed by reviewing transcriptomic studies performed on neuronal cells and on postmortem brains. We report some genes which expression is altered by cocaine that also bear genetic risk variants for the disorder. Finally, we have a glance to the pharmacogenetics of CUD treatments, still in early stages. A better understanding of the genetic underpinnings of CUD will foster the search of effective treatments and help to move forward to personalized medicine.

Psychiatric disorders are highly prevalent and display considerable clinical and genetic overlap. Dopaminergic and serotonergic neurotransmission have been shown to play an important role in many psychiatric disorders. Here we aim to assess the genetic contribution of these systems to eight psychiatric disorders (attention-deficit hyperactivity disorder (ADHD), anorexia nervosa (ANO), autism spectrum disorder (ASD), bipolar disorder (BIP), major depression (MD), obsessive-compulsive disorder (OCD), schizophrenia (SCZ) and Tourette's syndrome (TS)) using publicly available GWAS analyses performed by the Psychiatric Genomics Consortium that include more than 160,000 cases and 275,000 controls. To do so, we elaborated four different gene sets: two 'wide' selections for dopamine (DA) and for serotonin (SERT) using the Gene Ontology and KEGG pathways tools, and two'core' selections for the same systems, manually curated. At the gene level, we found 67 genes from the DA and/or SERT gene sets significantly associated with one of the studied disorders, and 12 of them were associated with two different disorders. Gene-set analysis revealed significant associations for ADHD and ASD with the wide DA gene set, for BIP with the wide SERT gene set, and for MD with the core SERT set. Interestingly, interrogation of a cross-disorder GWAS meta-analysis of the eight psychiatric conditions displayed association with the wide DA gene set. To our knowledge, this is the first systematic examination of genes encoding proteins essential to the function of these two neurotransmitter systems in these disorders. Our results support a pleiotropic contribution of the dopaminergic and serotonergic systems in several psychiatric conditions.

Cocaine addiction causes serious health problems, and no effective treatment is available yet. We previously identified a genetic risk variant for cocaine addiction in the PLCB1 gene and found this gene upregulated in postmortem brains of cocaine abusers and in human dopaminergic neuron-like cells after an acute cocaine exposure. Here, we functionally tested the contribution of the PLCB1 gene to cocaine addictive properties using Plcb1+/- mice. First, we performed a general phenotypic characterization and found that Plcb1+/- mice showed normal behavior, although they had increased anxiety and impaired short-term memory. Subsequently, mice were trained for operant conditioning, self-administered cocaine for 10 days, and were tested for cocaine motivation. After extinction, we found a reduction in the cue-induced reinstatement of cocaine-seeking behavior in Plcb1+/- mice. After reinstatement, we identified transcriptomic alterations in the medial prefrontal cortex of Plcb1+/- mice, mostly related to pathways relevant to addiction like the dopaminergic synapse and long-term potentiation. To conclude, we found that heterozygous deletion of the Plcb1 gene decreases cue-induced reinstatement of cocaine-seeking, pointing at PLCB1 as a possible therapeutic target for preventing relapse and treating cocaine addiction.

Genome-wide association studies have discovered hundreds of loci associated with complex brain disorders, but it remains unclear in which cell types these loci are active. Here we integrate genome-wide association study results with single-cell transcriptomic data from the entire mouse nervous system to systematically identify cell types underlying brain complex traits. We show that psychiatric disorders are predominantly associated with projecting excitatory and inhibitory neurons. Neurological diseases were associated with different cell types, which is consistent with other lines of evidence. Notably, Parkinson’s disease was genetically associated not only with cholinergic and monoaminergic neurons (which include dopaminergic neurons) but also with enteric neurons and oligodendrocytes. Using post-mortem brain transcriptomic data, we confirmed alterations in these cells, even at the earliest stages of disease progression. Our study provides an important framework for understanding the cellular basis of complex brain maladies, and reveals an unexpected role of oligodendrocytes in Parkinson’s disease. Eating Disorders Working Group of the Psychiatric Genomics Consortium Roger Adan17,18,19, Lars Alfredsson20, Tetsuya Ando21, Ole Andreassen22, Jessica Baker9, Andrew Bergen23,24, Wade Berrettini25, Andreas Birgegård26,27, Joseph Boden28, Ilka Boehm29, Claudette Boni30, Vesna Boraska Perica31,32, Harry Brandt33, Gerome Breen13,14, Julien Bryois1, Katharina Buehren34, Cynthia Bulik1,9,15, Roland Burghardt35, Matteo Cassina36, Sven Cichon37, Maurizio Clementi36, Jonathan Coleman13,14, Roger Cone38, Philippe Courtet39, Steven Crawford33, Scott Crow40, James Crowley16,26, unna Danner18, Oliver Davis41,42, Martina de Zwaan43, George Dedoussis44, Daniela Degortes45, Janiece DeSocio46, Danielle Dick47, Dimitris Dikeos48, Christian Dina49,50, Monika Dmitrzak-Weglarz51, Elisa Docampo Martinez52,53,54, Laramie Duncan55, Karin Egberts56, Stefan Ehrlich29, Geòrgia Escaramís52,53,54, Tõnu Esko57,58, Xavier Estivill52,53,54,59, Anne Farmer13, Angela Favaro45, Fernando Fernández-Aranda60,61, Manfred Fichter62,63, Krista Fischer57, Manuel Föcker64, Lenka Foretova65, Andreas Forstner37,66,67,68,69, Monica Forzan36, Christopher Franklin31, Steven Gallinger70, Héléna Gaspar13,14, Ina Giegling71, Johanna Giuranna64, Paola Giusti-Rodríquez16, Fragiskos Gonidakis72, Scott Gordon73, Philip Gorwood30,74, Monica Gratacos Mayora52,53,54, Jakob Grove75,76,77,78, Sébastien Guillaume39, Yiran Guo79, Hakon Hakonarson79,80, Katherine Halmi81, Ken Hanscombe82, Konstantinos Hatzikotoulas31, Joanna Hauser83, Johannes Hebebrand64, Sietske Helder13,84, Anjali Henders85, Stefan Herms37,69, Beate Herpertz-Dahlmann34, Wolfgang Herzog86, Anke Hinney64, L. John Horwood28, Christopher Hübel1,13, Laura Huckins31,87, James Hudson88, Hartmut Imgart89, Hidetoshi Inoko90, Vladimir Janout91, Susana Jiménez-Murcia60,61, Craig Johnson92, Jennifer Jordan93,94, Antonio Julià95, Anders Juréus1, Gursharan Kalsi13, Deborah Kaminská96, Allan Kaplan97, Jaakko Kaprio98,99, Leila Karhunen100, Andreas Karwautz101, Martien Kas17,102, Walter Kaye103, James Kennedy97, Martin Kennedy104, Anna Keski-Rahkonen98, Kirsty Kiezebrink105, Youl-Ri Kim106, Katherine Kirk73, Lars Klareskog107, Kelly Klump108, Gun Peggy Knudsen109, Maria La Via9, Mikael Landén1,19, Janne Larsen76,110,111, Stephanie Le Hellard112,113,114, Virpi Leppä1, Robert Levitan115, Dong Li79, Paul Lichtenstein1, Lisa Lilenfeld116, Bochao Danae Lin17, Jolanta Lissowska117, Jurjen Luykx17, Pierre Magistretti118,119, Mario Maj120, Katrin Mannik57,121, Sara Marsal95, Christian Marshall122, Nicholas Martin73, Manuel Mattheisen26,27,75,123, Morten Mattingsdal22, Sara McDevitt124,125, Peter McGuffin13, Sarah Medland73, Andres Metspalu57,126, Ingrid Meulenbelt127, Nadia Micali128,129, James Mitchell130, Karen Mitchell131, Palmiero Monteleone132, Alessio Maria Monteleone120, Grant Montgomery73,85,133, Preben Bo Mortensen76,110,111, Melissa Munn-Chernoff9, Benedetta Nacmias134, Marie Navratilova65, Claes Norring26,27, Ioanna Ntalla44, Catherine Olsen73, Roel Ophoff17,135, Julie O’Toole136, Leonid Padyukov107, Aarno Palotie58,99,137, Jacques Pantel30, Hana Papezova96, Richard Parker73, John Pearson138, Nancy Pedersen1, Liselotte Petersen76,110,111, Dalila Pinto87, Kirstin Purves13, Raquel Rabionet139,140,141, Anu Raevuori98, Nicolas Ramoz30, Ted Reichborn-Kjennerud109,142, Valdo Ricca134,143, Samuli Ripatti144, Stephan Ripke145,146,147, Franziska Ritschel29,148, Marion Roberts13, Alessandro Rotondo149, Dan Rujescu62,71, Filip Rybakowski150, Paolo Santonastaso151, André Scherag152, Stephen Scherer153, ulrike Schmidt13, Nicholas Schork154, Alexandra Schosser155, Jochen Seitz34, Lenka Slachtova156, P. Eline Slagboom127, Margarita Slof-Op ‘t Landt157,158, Agnieszka Slopien159, Sandro Sorbi134,160, Michael Strober161,162, Garret Stuber9,163, Patrick Sullivan1,16, Beata Świątkowska164, Jin Szatkiewicz16, Ioanna Tachmazidou31, Elena Tenconi45, Laura Thornton9, Alfonso Tortorella165,166, Federica Tozzi167, Janet Treasure13, Artemis Tsitsika168, Marta Tyszkiewicz-Nwafor150, Konstantinos Tziouvas169, Annemarie van Elburg18,170, Eric van Furth157,158, Tracey Wade171, Gudrun Wagner101, Esther Walton29, Hunna Watson9,10,11, Thomas Werge172, David Whiteman73, Elisabeth Widen99, D. Blake Woodside173,174, Shuyang Yao1, Zeynep Yilmaz9,16, Eleftheria Zeggini31,175, Stephanie Zerwas9 and Stephan Zipfel176 17Brain Center Rudolf Magnus, Department of Translational Neuroscience, University Medical Center Utrecht, Utrecht, the Netherlands. 18Center for Eating Disorders Rintveld, Altrecht Mental Health Institute, Zeist, the Netherlands. 19Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. 20Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden. 21Department of Behavioral Medicine, National Institute of Mental Health, National Center of Neurology and Psychiatry, Tokyo, Japan. 22NORMENT KG Jebsen Centre, Division of Mental Health and Addiction, University of Oslo, Oslo University Hospital, Oslo, Norway. 23BioRealm, LLC, Walnut, CA, USA. 24Oregon Research Institute, Eugene, OR, USA. 25Department of Psychiatry, Center for Neurobiology and Behavior, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA. 26Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden. 27Center for Psychiatry Research, Stockholm Health Care Services, Stockholm City Council, Stockholm, Sweden. 28Christchurch Health and Development Study, University of Otago, Christchurch, New Zealand. 29Division of Psychological and Social Medicine and Developmental Neurosciences, Faculty of Medicine, Technische Universität Dresden, Dresden, Germany. 30INSERM U894, Centre of Psychiatry and Neuroscience, Paris, France. 31Wellcome Sanger Institute, Hinxton, Cambridge, UK. 32Department of Medical Biology, School of Medicine, University of Split, Split, Croatia. 33The Center for Eating Disorders at Sheppard Pratt, Baltimore, MD, USA. 34Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, RWTH Aachen University, Aachen, Germany. 35Klinikum Frankfurt/Oder, Frankfurt, Germany. 36Clinical Genetics Unit, Department of Woman and Child Health, University of Padova, Padua, Italy. 37Institute of Medical Genetics and Pathology, University Hospital Basel, Basel, Switzerland. 38Life Sciences Institute and Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA. 39Department of Emergency Psychiatry and Post-Acute Care, CHRU Montpellier, University of Montpellier, Montpellier, France. 40Department of Psychiatry, University of Minnesota, Minneapolis, MN, USA. 41MRC Integrative Epidemiology Unit, University of Bristol, Bristol, UK. 42School of Social and Community Medicine, University of Bristol, Bristol, UK. 43Department of Psychosomatic Medicine and Psychotherapy, Hannover Medical School, Hannover, Germany. 44Department of Nutrition and Dietetics, Harokopio University, Athens, Greece. 45Department of Neurosciences, University of Padova, Padua, Italy. 46College of Nursing, Seattle University, Seattle, WA, USA. 47Department of Psychology, Virginia Commonwealth University, Richmond, VA, USA. 48Department of Psychiatry, Athens University Medical School, Athens University, Athens, Greece. 49L’institut du thorax, INSERM, CNRS, UNIV Nantes, Nantes, France. 50L’institut du thorax, CHU Nantes, Nantes, France. 51Department of Psychiatric Genetics, Poznań University of Medical Sciences, Poznań, Poland. 52Barcelona Institute of Science and Technology, Barcelona, Spain. 53Universitat Pompeu Fabra, Barcelona, Spain. 54Centro de Investigación Biomédica en Red en Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain. 55Department of Psychiatry and Behavioral Sciences, Stanford University Stanford, CA, USA. 56Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital of Würzburg, Centre for Mental Health, Würzburg, Germany. 57Estonian Genome Center, University of Tartu, Tartu, Estonia. 58Program in Medical and Population Genetics, Broad Institute of the Massachusetts Institute of Technology and Harvard University, Cambridge, MA, USA. 59Genomics and Disease, Bioinformatics and Genomics Programme, Centre for Genomic Regulation, Barcelona, Spain. 60Department of Psychiatry, University Hospital of Bellvitge –IDIBELL and CIBERobn, Barcelona, Spain. 61Department of Clinical Sciences, School of Medicine, University of Barcelona, Barcelona, Spain. 62Department of Psychiatry and Psychotherapy, Ludwig-Maximilians-University (LMU), Munich, Germany. 63Schön Klinik Roseneck affiliated with the Medical Faculty of the University of Munich (LMU), Munich, Germany. 64Department of Child and Adolescent Psychiatry, University Hospital Essen, University of Duisburg-Essen, Essen, Germany. 65Department of Cancer, Epidemiology and Genetics, Masaryk Memorial Cancer Institute, Brno, Czech Republic. 66Institute of Human Genetics, University of Bonn School of Medicine & University Hospital Bonn, Bonn, Germany. 67Department of Genomics, Life and Brain Center, University of Bonn, Bonn, Germany. 68Department of Psychiatry (UPK), University of Basel, Basel, Switzerland. 69Department of Biomedicine, University of Basel, Basel, Switzerland. 70Department of Surgery, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada. 71Department of Psychiatry, Psychotherapy and Psychosomatics, Martin Luther University of Halle-Wittenberg, Halle, Germany. 721st Psychiatric Department, National and Kapodistrian University of Athens, Medical School, Eginition Hospital, Athens, Greece. 73QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia. 74CMME (Groupe Hospitalier Sainte-Anne), Paris Descartes University, Paris, France. 75Department of Biomedicine, Aarhus University, Aarhus, Denmark. 76The Lundbeck Foundation Initiative for Integrative Psychiatric Research (iPSyCH), Aarhus, Denmark. 77Centre for Integrative Sequencing, iSEQ, Aarhus University, Aarhus, Denmark. 78Bioinformatics Research Centre, Aarhus University, Aarhus, Denmark. 79Center for Applied Genomics, Children’s Hospital of Philadelphia, Philadelphia, PA, USA. 80Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. 81Department of Psychiatry, Weill Cornell Medical College, New york, Ny, USA. 82Department of Medical and Molecular Genetics, King’s College London, Guy’s Hospital, London, UK. 83Department of Adult Psychiatry, Poznań University of Medical Sciences, Poznań, Poland. 84Zorg op Orde, Leidschendam, the Netherlands. 85Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, Australia. 86Department of General Internal Medicine and Psychosomatics, Heidelberg University Hospital, Heidelberg University, Heidelberg, Germany. 87Department of Psychiatry, and Genetics and Genomics Sciences, Division of Psychiatric Genomics, Icahn School of Medicine at Mount Sinai, New york, Ny, USA. 88Biological Psychiatry Laboratory, McLean Hospital/Harvard Medical School, Boston, MA, USA. 89Eating Disorders Unit, Parklandklinik, Bad Wildungen, Germany. 90Department of Molecular Life Science, Division of Basic Medical Science and Molecular Medicine, School of Medicine, Tokai University, Isehara, Japan. 91Faculty of Health Sciences, Palacky University, Olomouc, Czech Republic. 92Eating Recovery Center, Denver, CO, USA. 93Department of Psychological Medicine, University of Otago, Christchurch, New Zealand. 94Canterbury District Health Board, Christchurch, New Zealand. 95Rheumatology Research Group, Vall d’Hebron Research Institute, Barcelona, Spain. 96Department of Psychiatry, First Faculty of Medicine, Charles University, Prague, Czech Republic. 97Center for Addiction and Mental Health, Department of Psychiatry, Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada. 98Department of Public Health, University of Helsinki, Helsinki, Finland. 99Institute for Molecular Medicine Finland, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland. 100Institute of Public Health and Clinical Nutrition, Department of Clinical Nutrition, University of Eastern Finland, Kuopio, Finland. 101Eating Disorders Unit, Department of Child and Adolescent Psychiatry, Medical University of Vienna, Vienna, Austria. 102Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands. 103Department of Psychiatry, University of California San Diego, San Diego, CA, USA. 104Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand. 105Health Services Research Unit, University of Aberdeen, Aberdeen, UK. 106Department of Psychiatry, Seoul Paik Hospital, Inje University, Seoul, Korea. 107Rheumatology Unit, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden. 108Department of Psychology, Michigan State University, East Lansing, MI, USA. 109Department of Mental Disorders, Norwegian Institute of Public Health, Oslo, Norway. 110National Centre for Register-Based Research, Aarhus BSS, Aarhus University, Aarhus, Denmark. 111Centre for Integrated Register-based Research (CIRRAU), Aarhus University, Aarhus, Denmark. 112Department of Clinical Science, K.G. Jebsen Centre for Psychosis Research, Norwegian Centre for Mental Disorders Research (NORMENT), University of Bergen, Bergen, Norway. 113Dr. Einar Martens Research Group for Biological Psychiatry, Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway. 114Department of Clinical Medicine, Laboratory Building, Haukeland University Hospital, Bergen, Norway. 115Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada. 116American School of Professional Psychology, Argosy University, Northern Virginia, Arlington, VA, USA. 117Department of Cancer Epidemiology and Prevention, M Skłodowska-Curie Cancer Center - Oncology Center, Warsaw, Poland. 118BESE Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia. 119Department of Psychiatry, University of Lausanne-University Hospital of Lausanne (UNIL-CHUV), Lausanne, Switzerland. 120Department of Psychiatry, University of Campania ‘Luigi Vanvitelli’, Naples, Italy. 121Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland. 122Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada. 123Department of Psychiatry, Psychosomatics and Psychotherapy, University of Würzburg, Würzburg, Germany. 124Department of Psychiatry, University College Cork, Cork, Ireland. 125Eist Linn Adolescent Unit, Bessborough, Health Service Executive South, Cork, Ireland. 126Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia. 127Molecular Epidemiology Section (Department of Medical Statistics), Leiden University Medical Centre, Leiden, the Netherlands. 128Department of Psychiatry, Faculty of Medicine, University of Geneva, Geneva, Switzerland. 129Division of Child and Adolescent Psychiatry, Geneva University Hospital, Geneva, Switzerland. 130Department of Psychiatry and Behavioral Science, University of North Dakota School of Medicine and Health Sciences, Fargo, ND, USA. 131National Center for PTSD, VA Boston Healthcare System, Department of Psychiatry, Boston University School of Medicine, Boston, MA, USA. 132Department of Medicine, Surgery and Dentistry ‘Scuola Medica Salernitana’, University of Salerno, Salerno, Italy. 133Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia. 134Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), University of Florence, Florence, Italy. 135Center for Neurobehavioral Genetics, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, CA, USA. 136Kartini Clinic, Portland, OR, USA. 137Center for Human Genome Research at the Massachusetts General Hospital, Boston, MA, USA. 138Biostatistics and Computational Biology Unit, University of Otago, Christchurch, New Zealand. 139Saint Joan de Déu Research Institute, Saint Joan de Déu Barcelona Children’s Hospital, Barcelona, Spain. 140Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain. 141Department of Genetics, Microbiology and Statistics, University of Barcelona, Barcelona, Spain. 142Institute of Clinical Medicine, University of Oslo, Oslo, Norway. 143Department of Health Science, University of Florence, Florence, Italy. 144Department of Biometry, University of Helsinki, Helsinki, Finland. 145Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA, USA. 146Stanley Center for Psychiatric Research, Broad Institute of the Massachusetts Institute of Technology and Harvard University, Cambridge, MA, USA. 147Department of Psychiatry and Psychotherapy, Charité - Universitätsmedizin, Berlin, Germany. 148Eating Disorders Research and Treatment Center, Department of Child and Adolescent Psychiatry, Faculty of Medicine, Technische Universität Dresden, Dresden, Germany. 149Department of Psychiatry, Neurobiology, Pharmacology, and Biotechnologies, University of Pisa, Pisa, Italy. 150Department of Psychiatry, Poznań University of Medical Sciences, Poznań, Poland. 151Department of Neurosciences, Padua Neuroscience Center, University of Padova, Padua, Italy. 152Institute of Medical Statistics, Computer and Data Sciences, Jena University Hospital, Jena, Germany. 153Department of Genetics and Genomic Biology, The Hospital for Sick Children, Toronto, Ontario, Canada. 154J. Craig Venter Institute (JCVI), La Jolla, CA, USA. 155Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria. 156Department of Pediatrics and Center of Applied Genomics, First Faculty of Medicine, Charles University, Prague, Czech Republic. 157Center for Eating Disorders Ursula, Rivierduinen, Leiden, the Netherlands. 158Department of Psychiatry, Leiden University Medical Centre, Leiden, the Netherlands. 159Department of Child and Adolescent Psychiatry, Poznań University of Medical Sciences, Poznań, Poland. 160IRCCS Fondazione Don Carlo Gnocchi, Florence, Italy. 161Department of Psychiatry and Biobehavioral Science, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, CA, USA. 162David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA. 163Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. 164Department of Environmental Epidemiology, Nofer Institute of Occupational Medicine, Lodz, Poland. 165Department of Psychiatry, University of Naples SUN, Naples, Italy. 166Department of Psychiatry, University of Perugia, Perugia, Italy. 167Brain Sciences Department, Stremble Ventures, Limassol, Cyprus. 168Adolescent Health Unit, Second Department of Pediatrics, ‘P. & A. Kyriakou’ Children’s Hospital, University of Athens, Athens, Greece. 169Pediatric Intensive Care Unit, ‘P. & A. Kyriakou’ Children’s Hospital, University of Athens, Athens, Greece. 170Faculty of Social and Behavioral Sciences, Utrecht University, Utrecht, the Netherlands. 171School of Psychology, Flinders University, Adelaide, South Australia, Australia. 172Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark. 173Department of Psychiatry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada. 174Toronto General Hospital, Toronto, Ontario, Canada. 175Institute of Translational Genomics, Helmholtz Zentrum München, Neuherberg, Germany. 176Department of Internal Medicine VI, Psychosomatic Medicine and Psychotherapy, University Medical Hospital Tübingen, Tübingen, Germany International Headache Genetics Consortium Verneri Anttila177, Ville Artto178, Andrea Carmine Belin179, Irene de Boer180, Dorret I. Boomsma181, Sigrid Børte182, Daniel I. Chasman183, Lynn Cherkas184, Anne Francke Christensen185, Bru Cormand186, Ester Cuenca-Leon177, George Davey-Smith187, Martin Dichgans188, Cornelia van Duijn189, Tonu Esko57, Ann Louise Esserlind190, Michel Ferrari180, Rune R. Frants180, Tobias Freilinger191, Nick Furlotte192, Padhraig Gormley177, Lyn Griffiths193, Eija Hamalainen194, Thomas Folkmann Hansen6, Marjo Hiekkala195, M. Arfan Ikram189, Andres Ingason196, Marjo-Riitta Järvelin197, Risto Kajanne194, Mikko Kallela178, Jaakko Kaprio98,99, Mari Kaunisto195, Lisette J. A. Kogelman6, Christian Kubisch198, Mitja Kurki177, Tobias Kurth199, Lenore Launer200, Terho Lehtimaki201, Davor Lessel198, Lannie Ligthart181, Nadia Litterman192, Arn van den Maagdenberg180, Alfons Macaya202, Rainer Malik188, Massimo Mangino184, George McMahon187, Bertram Muller-Myhsok203, Benjamin M. Neale177, Carrie Northover192, Dale R. Nyholt193, Jes Olesen190, Aarno Palotie58,99,137, Priit Palta194, Linda Pedersen182, Nancy Pedersen1, Danielle Posthuma181, Patricia Pozo-Rosich204, Alice Pressman205, Olli Raitakari206, Markus Schürks199, Celia Sintas186, Kari Stefansson196, Hreinn Stefansson196, Stacy Steinberg196, David Strachan207, Gisela Terwindt180, Marta Vila-Pueyo202, Maija Wessman195, Bendik S. Winsvold182, Huiying Zhao193 and John Anker Zwart182 177Broad Institute of MIT and Harvard, Cambridge, MA, USA. 178Department of Neurology, Helsinki University Central Hospital, Helsinki, Finland. 179Karolinska Institutet, Stockholm, Sweden. 180Leiden University Medical Centre, Leiden, the Netherlands. 181VU University, Amsterdam, the Netherlands. 182Oslo University Hospital and University of Oslo, Oslo, Norway. 183Harvard Medical School, Cambridge, MA, USA. 184Department of Twin Research and Genetic Epidemiology, King’s College London, London, UK. 185Danish Headache Center, Copenhagen University Hospital, Copenhagen, Denmark. 186University of Barcelona, Barcelona, Spain. 187Medical Research Council (MRC) Integrative Epidemiology Unit, University of Bristol, Bristol, UK. 188Institute for Stroke and Dementia Research, Munich, Germany. 189Erasmus University Medical Centre, Rotterdam, the Netherlands. 190Danish Headache Center, Department of Neurology, Rigshospitalet, Glostrup, Denmark. 191University of Tübingen, Tübingen, Germany. 19223&Me Inc., Mountain View, CA, USA. 193Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia. 194Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland. 195Folkhälsan Institute of Genetics, Helsinki, Finland. 196Decode genetics Inc., Reykjavik, Iceland. 197University of Oulu, Biocenter Oulu, Finland. 198University Medical Center Hamburg-Eppendorf, Hamburg, Germany. 199Harvard Medical School, Boston, MA, USA. 200National Institute on Aging, Bethesda, MD, USA. 201School of Medicine, University of Tampere, Tampere, Finland. 202Vall d’Hebron Research Institute, Barcelona, Spain. 203Max Planck Institute of Psychiatry, Munich, Germany. 204Headache Research Group, Universitat Autònoma de Barcelona, Barcelona, Spain. 205Sutter Health, Sacramento, CA, USA. 206Department of Medicine, University of Turku, Turku, Finland. 207Population Health Research Institute, St George’s University of London, London, UK. 23andMe Research Team Michelle Agee208, Babak Alipanahi208, Adam Auton208, Robert Bell208, Katarzyna Bryc208, Sarah Elson208, Pierre Fontanillas208, Nicholas Furlotte208, Karl Heilbron208, David Hinds208, Karen Huber208, Aaron Kleinman208, Nadia Litterman208, Jennifer McCreight208, Matthew McIntyre208, Joanna Mountain208, Elizabeth Noblin208, Carrie Northover208, Steven Pitts208, J. Sathirapongsasuti208, Olga Sazonova208, Janie Shelton208, Suyash Shringarpure208, Chao Tian208, Joyce Tung208, Vladimir Vacic208 and Catherine Wilson208 20823andMe, Inc., Mountain View, CA, US

Attention deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder characterized by age-inappropriate symptoms of inattention, impulsivity, and hyperactivity that persist into adulthood in the majority of the diagnosed children. Despite several risk factors during childhood predicting the persistence of ADHD symptoms into adulthood, the genetic architecture underlying the trajectory of ADHD over time is still unclear. We set out to study the contribution of common genetic variants to the risk for ADHD across the lifespan by conducting meta-analyses of genome-wide association studies on persistent ADHD in adults and ADHD in childhood separately and jointly, and by comparing the genetic background between them in a total sample of 17,149 cases and 32,411 controls. Our results show nine new independent loci and support a shared contribution of common genetic variants to ADHD in children and adults. No subgroup heterogeneity was observed among children, while this group consists of future remitting and persistent individuals. We report similar patterns of genetic correlation of ADHD with other ADHD-related datasets and different traits and disorders among adults, children, and when combining both groups. These findings confirm that persistent ADHD in adults is a neurodevelopmental disorder and extend the existing hypothesis of a shared genetic architecture underlying ADHD and different traits to a lifespan perspective.

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder caused by an interplay of genetic and environmental factors. Epigenetics is crucial to lasting changes in gene expression in the brain. Recent studies suggest a role for DNA methylation in ADHD. We explored the contribution to ADHD of allele-specific methylation (ASM), an epigenetic mechanism that involves SNPs correlating with differential levels of DNA methylation at CpG sites. We selected 3896 tagSNPs reported to influence methylation in human brain regions and performed a case-control association study using the summary statistics from the largest GWAS meta-analysis of ADHD, comprising 20,183 cases and 35,191 controls. We observed that genetic risk variants for ADHD are enriched in ASM SNPs and identified associations with eight tagSNPs that were significant at a 5% false discovery rate (FDR). These SNPs correlated with methylation of CpG sites lying in the promoter regions of six genes. Since methylation may affect gene expression, we inspected these ASM SNPs together with 52 ASM SNPs in high LD with them for eQTLs in brain tissues and observed that the expression of three of those genes was affected by them. ADHD risk alleles correlated with increased expression (and decreased methylation) of ARTN and PIDD1 and with a decreased expression (and increased methylation) of C2orf82. Furthermore, these three genes were predicted to have altered expression in ADHD, and genetic variants in C2orf82 correlated with brain volumes. In summary, we followed a systematic approach to identify risk variants for ADHD that correlated with differential cis-methylation, identifying three novel genes contributing to the disorder.

Cocaine is one of the most used psychostimulant drugs worldwide. MicroRNAs are post-transcriptional regulators of gene expression that are highly expressed in brain, and several studies have shown that cocaine can alter their expression. In a previous study, we identified several protein-coding genes that are differentially expressed in a dopaminergic neuron-like model after an acute exposure to cocaine. Now, we used the prediction tool WebGestalt to identify miRNA molecules potentially involved in the regulation of these genes. Using the same cellular model, we found that seven of these miRNAs are down-regulated by cocaine: miR-124-3p, miR-124-5p, miR-137, miR-101-3p, miR-9-5p, miR-369-3p and miR-153-3p, the last three not previously related to cocaine. Furthermore, we found that three of the miRNA genes that are differentially expressed in our model (hsa-miR-9-1, hsa-miR-153-1 and hsa-miR-124-3) are nominally associated with cocaine dependence in a case-control study (2,085 cases and 4,293 controls). In summary, we highlighted novel miRNAs that may be involved in those cocaine-induced changes of gene expression that underlie addiction. Moreover, we identified genetic variants that contribute to cocaine dependence in three of these miRNA genes, supporting the idea that genes differentially expressed under cocaine may play an important role in the susceptibility to cocaine dependence.

De novo FOXP1 mutations have been associated with intellectual disability (ID), motor delay, autistic features and a wide spectrum of speech difficulties. C syndrome (Opitz C trigonocephaly syndrome) is a rare and genetically heterogeneous condition, characterized by trigonocephaly, craniofacial anomalies and ID. Several different chromosome deletions and and point mutations in distinct genes have been associated with the disease in patients originally diagnosed as Opitz C. By whole exome sequencing we identified a de novo splicing mutation in FOXP1 in a patient, initially diagnosed as C syndrome, who suffers from syndromic intellectual disability with trigonocephaly. The mutation (c.1428 + 1 G > A) promotes the skipping of exon 16, a frameshift and a premature STOP codon (p.Ala450GLyfs*13), as assessed by a minigene strategy. The patient reported here shares speech difficulties, intellectual disability and autistic features with other FOXP1 syndrome patients, and thus the diagnosis for this patient should be changed. Finally, since trigonocephaly has not been previously reported in FOXP1 syndrome, it remains to be proved whether it may be associated with the FOXP1 mutation.

Methylphenidate (MPH) is the most frequently used pharmacological treatment in children with attention-deficit/hyperactivity disorder (ADHD). However, a considerable interindividual variability exists in clinical outcome. Thus, we performed a genome-wide association study of MPH efficacy in 173 ADHD paediatric patients. Although no variant reached genome-wide significance, the set of genes containing single-nucleotide polymorphisms (SNPs) nominally associated with MPH response (P < 0.05) was significantly enriched for candidates previously studied in ADHD or treatment outcome. We prioritised the nominally significant SNPs by functional annotation and expression quantitative trait loci (eQTL) analysis in human brain, and we identified 33 SNPs tagging cis-eQTL in 32 different loci (referred to as eSNPs and eGenes, respectively). Pathway enrichment analyses revealed an over-representation of genes involved in nervous system development and function among the eGenes. Categories related to neurological diseases, psychological disorders and behaviour were also significantly enriched. We subsequently meta-analysed the association with clinical outcome for the 33 eSNPs across the discovery sample and an independent cohort of 189 ADHD adult patients (target sample) and we detected 15 suggestive signals. Following this comprehensive strategy, our results provide a better understanding of the molecular mechanisms implicated in MPH treatment effects and suggest promising candidates that may encourage future studies.

Opitz trigonocephaly C syndrome (OTCS) is a rare genetic disorder characterized by craniofacial anomalies, variable intellectual and psychomotor disability, and variable cardiac defects with a high mortality rate. Different patterns of inheritance and genetic heterogeneity are known in this syndrome. Whole exome and genome sequencing of a 19-year-old girl (P7), initially diagnosed with OTCS, revealed a de novo nonsense mutation, p.Q638*, in the MAGEL2 gene. MAGEL2 is an imprinted, maternally silenced, gene located at 15q11-13, within the Prader-Willi region. Patient P7 carried the mutation in the paternal chromosome. Recently, mutations in MAGEL2 have been described in Schaaf-Yang syndrome (SHFYNG) and in severe arthrogryposis. Patient P7 bears resemblances with SHFYNG cases but has other findings not described in this syndrome and common in OTCS. We sequenced MAGEL2 in nine additional OTCS patients and no mutations were found. This study provides the first clear molecular genetic basis for an OTCS case, indicates that there is overlap between OTCS and SHFYNG syndromes, and confirms that OTCS is genetically heterogeneous. Genes encoding MAGEL2 partners, either in the retrograde transport or in the ubiquitination-deubiquitination complexes, are promising candidates as OTCS disease-causing genes. Funding was from Associació Síndrome Opitz C, Terrassa, Spain; Spanish Ministerio de Economía y Competitividad (SAF2014-56562-R; FECYT, crowdfunding PRECIPITA); Catalan Government (2014SGR932) and from CIBERER (U720). We acknowledge support of the Spanish Ministry of Economy and Competitiveness, 'Centro de Excelencia Severo Ochoa 2013-2017'.

Genetic factors involved in the susceptibility to drug addiction still remain largely unknown. MiRNAs seem to play key roles in the drug-induced plasticity of the brain that likely drives the emergence of addiction. In this work we explored the role of miRNAs in drug addiction. With this aim, we selected 62 SNPs located in the 3'UTR of target genes that are predicted to alter the binding of miRNA molecules and performed a case-control association study in a Spanish sample of 735 cases (mainly cocaine-dependent subjects with multiple drug dependencies) and 739 controls. We found an association between rs1047383 in the PLCB1 gene and drug dependence that was replicated in an independent sample (663 cases and 667 controls). Then we selected 9 miRNAs predicted to bind the rs1047383 region, but none of them showed any effect on PLCB1 expression. We also assessed two miRNAs binding a region that contains a SNP in linkage disequilibrium with rs1047383, but although one of them, hsa-miR-582, was found to downregulate PLCB1, no differences were observed between alleles. Finally, we explored the possibility that PLCB1 expression is altered by cocaine and we observed a significant upregulation of the gene in the nucleus accumbens of cocaine abusers and in human dopaminergic-like neurons after cocaine treatment. Our results, together with previous studies, suggest that PLCB1 participates in the susceptibility to drug dependence.

Attention Deficit Hyperactivity Disorder (ADHD) is a common childhood-onset neurodevelopmental condition characterized by pervasive impairment of attention, hyperactivity, and/or impulsivity that can persist into adulthood. The aetiology of ADHD is complex and multifactorial and, despite the wealth of evidence for its high heritability, genetic studies have provided modest evidence for the involvement of specific genes and have failed to identify consistent and replicable results. Due to the lack of robust findings, we performed gene-wide and pathway enrichment analyses using pre-existing GWAS data from 607 persistent ADHD subjects and 584 controls, produced by our group. Subsequently, expression profiles of genes surpassing a follow-up threshold of P-value < 1e-03 in the gene-wide analyses were tested in peripheral blood mononucleated cells (PBMCs) of 45 medication-naive adults with ADHD and 39 healthy unrelated controls. We found preliminary evidence for genetic association between RNF122 and ADHD and for its overexpression in adults with ADHD. RNF122 encodes for an E3 ubiquitin ligase involved in the proteasome-mediated processing, trafficking, and degradation of proteins that acts as an essential mediator of the substrate specificity of ubiquitin ligation. Thus, our findings support previous data that place the ubiquitin-proteasome system as a promising candidate for its involvement in the aetiology of ADHD.

Episodic ataxia is an autosomal dominant ion channel disorder characterized by episodes of imbalance and incoordination. The disease is genetically heterogeneous and is classified as episodic ataxia type 2 (EA2) when it is caused by a mutation in the CACNA1A gene, encoding the a(1A) subunit of the P/Q-type voltage-gated calcium channel Ca(v)2.1. The vast majority of EA2 disease-causing variants are loss-of-function (LoF) point changes leading to decreased channel currents. CACNA1A exonic deletions have also been reported in EA2 using quantitative approaches. We performed a mutational screening of the CACNA1A gene, including the promoter and 3'UTR regions, in 49 unrelated patients diagnosed with episodic ataxia. When pathogenic variants were not found by sequencing, we performed a copy number variant (CNV) analysis to screen for duplications or deletions. Overall, sequencing screening allowed identification of six different point variants (three nonsense and three missense changes) and two coding indels, one of them found in two unrelated patients. Additionally, CNV analysis identified a deletion in a patient spanning exon 35 as a result of a recombination event between flanking intronic Alu sequences. This study allowed identification of potentially pathogenic alterations in our sample, five of them novel, which cover 20% of the patients (10/49). Our data suggest that most of these variants are disease-causing, although functional studies are required.