C-reactive protein concentration in bipolar disorder: association with genetic variants

Ann-Kristin Evers,Andreas Reif,Rhiannon Mcneill,Sarah Kittel-Schneider,Julia Veeh

doi:10.1186/s40345-019-0162-z

Abstract

BackgroundSeveral recent studies have investigated the role of C-reactive protein (CRP) in bipolar disorder (BD), but few studies have directly investigated the interaction between CRP genetic variants and peripheral CRP concentration across different phases of BD. In this study, we aimed to replicate previous findings that demonstrated altered CRP levels in BD, and to investigate whether there is an association of peripheral protein expression with genetic variants in the CRP gene.Methods221 patients were included in the study, of which 183 (all episodes, 46 not medicated, 174 medicated) were genotyped for CRP single-nucleotide polymorphisms (SNPs) shown to influence peripheral CRP protein expression (rs1800947, rs2808630, rs1417938, rs1205).ResultsThere were no differences in CRP levels associated with the genotypes, only regarding the rs1205 SNP there were significantly different CRP protein expression between the genotypes when taking body mass index, age, BD polarity, subtype and leukocyte number into account. However, we could show significantly elevated CRP protein expression in manic patients compared to euthymic and depressed patients, independent from genotype. Medication was found to have no effect on CRP protein expression.ConclusionsThese results indicate that low grade inflammation might play a role in mania and might be rather a state than a trait marker of bipolar disorder.

Highlights

Several recent studies have investigated the role of C-reactive protein (CRP) in bipolar disorder (BD), but few studies have directly investigated the interaction between CRP genetic variants and peripheral CRP concen‐ tration across different phases of BD
Association of genetic variation in the CRP gene with serum CRP concentration We assessed if there were differences between the genotypes of four single-nucleotide polymorphisms (SNPs) in CRP levels (Table 2)
No significant differences in CRP levels were detected between different genotypes using non parametric Kruskal–Wallis analysis

Summary

Introduction

Several recent studies have investigated the role of C-reactive protein (CRP) in bipolar disorder (BD), but few studies have directly investigated the interaction between CRP genetic variants and peripheral CRP concen‐ tration across different phases of BD. Bipolar disorder (BD) is primarily a periodic disease that has a global burden (Ferrari et al 2016). It is characterized by the occurrence of (hypo-)manic and depressive episodes, and in a number of patients these mood states increase in frequency and severity over time, as well as decreasing responsiveness to treatment and that can result in a chronic course (Gildengers et al 2014). Developmental and environmental risk factors are thought to play a role in the pathogenesis of the disorder (Landgraf et al 2014)

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