Genome-wide association study of borderline personality disorder reveals genetic overlap with bipolar disorder, major depression and schizophrenia

Borderline personality disorder (BOR) is determined by environmental and genetic factors, and characterized by affective instability and impulsivity, diagnostic symptoms also observed in manic phases of bipolar disorder (BIP). Up to 20% of BIP patients show comorbidity with BOR. This report describes the first case-control genome-wide association study (GWAS) of BOR, performed in one of the largest BOR patient samples worldwide. The focus of our analysis was (i) to detect genes and gene sets involved in BOR and (ii) to investigate the genetic overlap with BIP. As there is considerable genetic overlap between BIP, major depression (MDD) and schizophrenia (SCZ) and a high comorbidity of BOR and MDD, we also analyzed the genetic overlap of BOR with SCZ and MDD. GWAS, gene-based tests and gene-set analyses were performed in 998 BOR patients and 1545 controls. Linkage disequilibrium score regression was used to detect the genetic overlap between BOR and these disorders. Single marker analysis revealed no significant association after correction for multiple testing. Gene-based analysis yielded two significant genes: DPYD (P=4.42 × 10-7) and PKP4 (P=8.67 × 10-7); and gene-set analysis yielded a significant finding for exocytosis (GO:0006887, PFDR=0.019; FDR, false discovery rate). Prior studies have implicated DPYD, PKP4 and exocytosis in BIP and SCZ. The most notable finding of the present study was the genetic overlap of BOR with BIP (rg=0.28 [P=2.99 × 10-3]), SCZ (rg=0.34 [P=4.37 × 10-5]) and MDD (rg=0.57 [P=1.04 × 10-3]). We believe our study is the first to demonstrate that BOR overlaps with BIP, MDD and SCZ on the genetic level. Whether this is confined to transdiagnostic clinical symptoms should be examined in future studies.

Differences in plasma concentration of acylethanolanydes and acylglycerols in paired samples of bipolar patients and first- and second-degree relatives

Introduction

Endocannabinoid System (ECS) has been highlighted as one of the most relevant research topics by neurobiologists, pharmacists, basic scientists and clinicians (Skaper and Di Marzo, 2012). Recent work has associated major depressive disorder with the ECS (Ashton and Moore, 2011). Despite the close relationship between depression and bipolar disorders, as far as we know, there is no characterization of ECS and congeners in a sample of patients with bipolar disorders.

Aims and objectives

The objective of this work is to characterize the plasma levels of endocannabinoids and congeners in a sample of patients with bipolar disorders.

Method

The clinical group was composed by 19 patients with a diagnosis of bipolar disorders using SCID-IV (First et al., 1999). The control group was formed by 18 relatives of first- or second-degree of the patients.

The following endocannabinoids and congeners were quantified: N-palmitoleoylethanolamide (POEA), N-palmitolylethanolamide (PEA), N-oleoylethanolamide (OEA), N-stearoylethanolamide (SEA), N-arachidonoylethanolamide (AEA), N-dihomo-γ-linolenoylethanolamide (DGLEA), N-docosatetraenoylethanolamide (DEA), N-linoleoylethanolamide (LEA), N-docosahexaenoylethanolamide (DHEA), 2-arachidonoylglycerol (2-AG), 2-linoleoylglycerol (2-LG), and 2-oleoylglycerol (2-OG).

Results

The result showed statistically significant lower levels of AEA, DEA and DHEA in clinical sample. Previous research also identified lower levels of AEA in depressed women (Hill et al., 2008, 2009). Until date, it is unknown if DEA and DHEA have some effect on EC receptors, and whether they have some direct effects on endocannabinoids.

Conclusions

It would be necessary to carry our other research with a larger sample, which could allow the control of potential confounding variables.

Disclosure of interest

The authors have not supplied their declaration of competing interest.