title: CDH13 and HCRTR2 May Be Associated with Hypersomnia Symptom of Bipolar Depression: A Genome-Wide Functional Enrichment Pathway Analysis.
abstract: Although bipolar disorder is highly heritable, the identification of specific genetic variations is limited because of the complex traits underlying the disorder. We performed a genome-wide association study of bipolar disorder using a subphenotype that shows hypersomnia symptom during a major depressive episode. We investigated a total of 2,191 cases, 1,434 controls, and 703,012 single nucleotide polymorphisms (SNPs) in the merged samples obtained from the Translational Genomics Institute and the Genetic Association Information Network. The gene emerging as the most significant by statistical analysis was rs1553441 (odds ratio=0.4093; p=1.20×10(-5); Permuted p=6.0×10(-6)). However, the 5×0(-8) threshold for statistical significance required in a genome-wide association study was not achieved. The functional enrichment pathway analysis showed significant enrichments in the adhesion, development-related, synaptic transmission-related, and cell recognition-related pathways. For further evaluation, each gene of the enriched pathways was reviewed and matched with genes that were suggested to be associated with psychiatric disorders by previous genetic studies. We found that the cadherin 13 and hypocretin (orexin) receptor 2 genes may be involved in the hypersomnia symptom during a major depressive episode of bipolar disorder.
authors.affiliation: Department of Psychiatry, Korea University College of Medicine, Seoul, Republic of Korea.
authors.forename: Chul-Hyun
authors.initials: CH
authors.lastname: Cho
authors.affiliation: Department of Psychiatry, Korea University College of Medicine, Seoul, Republic of Korea.
authors.forename: Heon-Jeong
authors.initials: HJ
authors.lastname: Lee
authors.affiliation: Department of Physiology, Ajou University School of Medicine, Suwon, Republic of Korea.
authors.forename: Hyun Goo
authors.initials: HG
authors.lastname: Woo
authors.affiliation: Department of Physiology, Ajou University School of Medicine, Suwon, Republic of Korea.
authors.forename: Ji-Hye
authors.initials: JH
authors.lastname: Choi
authors.affiliation: Department of Psychiatry, University of California San Diego, La Jolla, CA, USA.
authors.forename: Tiffany A
authors.initials: TA
authors.lastname: Greenwood
authors.affiliation: Department of Psychiatry, University of California San Diego, La Jolla, CA, USA. ; San Diego VA Healthcare System, San Diego, CA, USA.
authors.forename: John R
authors.initials: JR
authors.lastname: Kelsoe
keywords: Bipolar depression; Bipolar disorder; Functional enrichment pathway analysis; Genome-wide association study; Hypersomnia