The distribution of the MCP-1 A-2518G single nucleotide polymorphisms (SNP) was analyzed in a population of 212 patients with frontotemporal lobar degeneration (FTLD) compared with 203 age-matched controls. A significantly decreased allelic frequency of the G allele in patients compared with controls was observed (21.1 versus 29.3%, P = 0.011, OR: 0.59, CI: 0.40-0.87). Stratifying according to gender, the association was maintained in male patients versus male controls (17.8 versus 29.4%, P = 0.016, OR = 0.46, 95% CI: 0.25-0.84), but not in female patients compared with female controls (23.5 versus 29.2%, P > 0.05). The frequency of apolipoprotein E epsilon4 carriers was increased in patients (26.4 versus 13.8%, P = 0.0015, OR: 2.24, 95% CI: 1.37-3.67). Apolipoprotein E status did not influence the distribution of the A-2518G SNP. Monocyte chemotactic protein (MCP)-1 levels were determined in cerebrospinal fluid (CSF) collected from 23 patients and 17 controls. MCP-1 CSF levels were increased in patients compared with controls (449.01 +/- 27.57 versus 364.19 +/- 23.75 pg/ml, P = 0.011). Stratifying patients according to the presence of the polymorphic allele, significantly increased CSF MCP-1 levels were observed in carriers of the G allele compared with non-carriers (502.21 +/- 44.57 versus 395.87 +/- 21.92 pg/ml, P = 0.045). The MCP-1 A-2518G SNP acts as protective factor for sporadic FTLD, possibly by influencing MCP-1 production.