The MCP-1 Gene (SCYA2) and Mood Disorders: Preliminary Results of a Case-Control Association Study

The aim of this case-control study was to investigate the potential role of the A-2518G polymorphism of the gene of monocyte chemoattractant protein 1 (MCP-1, a cytokine playing an important role in innate immunity) in conferring susceptibility to mood disorders. The sample studied included 96 outpatients with DSM-IV-TR diagnosis of major depressive disorder, bipolar disorder I (BD I) or BD II and 161 matched healthy controls. All subjects were genotyped for the A-2518G polymorphism of the MCP-1 gene. Genotypic and allelic associations were explored between patients and controls and across the different diagnostic groups (χ 2 tests). No genotypic (χ 2 = 8.215, d.f. = 6, p = 0.223) or allelic (χ 2 = 5.058, d.f. = 3, p = 0.168) association for the A-2518G polymorphism of SCYA2 was found considering cases and controls. Nevertheless, important correlations were observed when patients were divided into diagnostic subgroups. A significantly higher frequency of the AA genotype (χ 2 = 7.233, d.f. = 2, p = 0.027) and of the A allele (χ 2 = 4.730, d.f. = 1, p = 0.030) was observed in subjects with BD. In addition, independently from diagnosis, a higher number of lifetime suicide attempts was found in subjects with the AA genotype of the A-2518G polymorphism of the MCP-1 gene (F = 3.802, p = 0.026). The present preliminary results, though limited by the relatively small sample, suggest a possible role of the SCYA2 in conferring susceptibility to BD and, if confirmed, may represent a biological discriminative influence between mood disorder subtypes.