Association of the iPLA2β Gene With Bipolar Disorder and Assessment of Its Interaction With TRPM2 Gene Polymorphisms

Document Type

Article

Publication Date

4-1-2013

Description

Altered intracellular calcium homeostasis and oxidative stress are involved in the pathophysiology of bipolar disorder (BD)-I. To explore the genes contributing to these abnormalities, we examined the association with BD of the iPLA2β (PLA2G6), a signaling enzyme that mobilizes the arachidonic acid signaling cascade and activates oxidative stress, and assessed whether it interacts genetically with type 2 transient receptor potential channel gene (TRPM2), an oxidative stress-responsive calcium channel implicated both functionally and genetically in BD-I. Two tag single nucleotide polymorphisms rs4375 and rs3788533 in iPLA2β were genotyped in 446 White case-control individuals and 296 BD families using a 5′-nuclease TaqMan assay. The results were analyzed using χ-test and transmission disequilibrium tests, and Haploview. In a secondary analysis, we tested gene-gene interactions between TRPM2 and iPLA2β on BD vulnerability by logistic regression using a case-only design in PLINK. iPLA2β-rs3788533 showed a borderline association with BD-I in patients with a history of psychosis in both case-control and family designs. Association with BD as a whole was observed in the family study (significant over transmissions of rs3788533-allele C, P=0.015, PBonferroni=0.03, TDTPHASE). A borderline interaction was found between rs749909 within TRPM2 and rs4375 within iPLA2β (Puncorrected=0.009), on the basis of the case-only design analyzed with PLINK. A significant association of iPLA2β variants with BD-I and a trend gene-gene interaction between iPLA2β and TRPM2 provides additional support for the notion that genetic variation in these two functionally implicated candidates contributes toward the risk and pathophysiology of this illness.

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