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Evidence for genetic heterogeneity between clinical subtypes of bipolar disorder.

ABSTRACT: We performed a genome-wide association study of 6447 bipolar disorder (BD) cases and 12 639 controls from the International Cohort Collection for Bipolar Disorder (ICCBD). Meta-analysis was performed with prior results from the Psychiatric Genomics Consortium Bipolar Disorder Working Group for a combined sample of 13 902 cases and 19 279 controls. We identified eight genome-wide significant, associated regions, including a novel associated region on chromosome 10 (rs10884920; P=3.28 × 10-8) that includes the brain-enriched cytoskeleton protein adducin 3 (ADD3), a non-coding RNA, and a neuropeptide-specific aminopeptidase P (XPNPEP1). Our large sample size allowed us to test the heritability and genetic correlation of BD subtypes and investigate their genetic overlap with schizophrenia and major depressive disorder. We found a significant difference in heritability of the two most common forms of BD (BD I SNP-h2=0.35; BD II SNP-h2=0.25; P=0.02). The genetic correlation between BD I and BD II was 0.78, whereas the genetic correlation was 0.97 when BD cohorts containing both types were compared. In addition, we demonstrated a significantly greater load of polygenic risk alleles for schizophrenia and BD in patients with BD I compared with patients with BD II, and a greater load of schizophrenia risk alleles in patients with the bipolar type of schizoaffective disorder compared with patients with either BD I or BD II. These results point to a partial difference in the genetic architecture of BD subtypes as currently defined.

SUBMITTER: Charney AW

PROVIDER: S-EPMC5545718 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature

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Evidence for genetic heterogeneity between clinical subtypes of bipolar disorder.

Charney A W AW Ruderfer D M DM Stahl E A EA Moran J L JL Chambert K K Belliveau R A RA Forty L L Gordon-Smith K K Di Florio A A Lee P H PH Bromet E J EJ Buckley P F PF Escamilla M A MA Fanous A H AH Fochtmann L J LJ Lehrer D S DS Malaspina D D Marder S R SR Morley C P CP Nicolini H H Perkins D O DO Rakofsky J J JJ Rapaport M H MH Medeiros H H Sobell J L JL Green E K EK Backlund L L Bergen S E SE Juréus A A Schalling M M Lichtenstein P P Roussos P P Knowles J A JA Jones I I Jones L A LA Hultman C M CM Perlis R H RH Purcell S M SM McCarroll S A SA Pato C N CN Pato M T MT Craddock N N Landén M M Smoller J W JW Sklar P P

Translational psychiatry 20170110 1

We performed a genome-wide association study of 6447 bipolar disorder (BD) cases and 12 639 controls from the International Cohort Collection for Bipolar Disorder (ICCBD). Meta-analysis was performed with prior results from the Psychiatric Genomics Consortium Bipolar Disorder Working Group for a combined sample of 13 902 cases and 19 279 controls. We identified eight genome-wide significant, associated regions, including a novel associated region on chromosome 10 (rs10884920; P=3.28 × 10<sup>-8< ...[more]

PMID: 28072414

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Project description:BackgroundBipolar disorder, particularly in children, is characterized by rapid cycling and switching, making circadian clock genes plausible molecular underpinnings for bipolar disorder. We previously reported work establishing mice lacking the clock gene D-box binding protein (DBP) as a stress-reactive genetic animal model of bipolar disorder. Microarray studies revealed that expression of two closely related clock genes, RAR-related orphan receptors alpha (RORA) and beta (RORB), was altered in these mice. These retinoid-related receptors are involved in a number of pathways including neurogenesis, stress response, and modulation of circadian rhythms. Here we report association studies between bipolar disorder and single-nucleotide polymorphisms (SNPs) in RORA and RORB.MethodsWe genotyped 355 RORA and RORB SNPs in a pediatric cohort consisting of a family-based sample of 153 trios and an independent, non-overlapping case-control sample of 152 cases and 140 controls. Bipolar disorder in children and adolescents is characterized by increased stress reactivity and frequent episodes of shorter duration; thus our cohort provides a potentially enriched sample for identifying genes involved in cycling and switching.ResultsWe report that four intronic RORB SNPs showed positive associations with the pediatric bipolar phenotype that survived Bonferroni correction for multiple comparisons in the case-control sample. Three RORB haplotype blocks implicating an additional 11 SNPs were also associated with the disease in the case-control sample. However, these significant associations were not replicated in the sample of trios. There was no evidence for association between pediatric bipolar disorder and any RORA SNPs or haplotype blocks after multiple-test correction. In addition, we found no strong evidence for association between the age-at-onset of bipolar disorder with any RORA or RORB SNPs.ConclusionOur findings suggest that clock genes in general and RORB in particular may be important candidates for further investigation in the search for the molecular basis of bipolar disorder.

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Evidence for genetic heterogeneity between clinical subtypes of bipolar disorder.

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Evidence for genetic heterogeneity between clinical subtypes of bipolar disorder.

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