Background and purpose: Interleukin 6 (IL-6) is one of the mediators of inflammation in the neurodegenerative process in Alzheimer's disease (AD). The aim of the study was to identify the risk of AD incidence in carriers of the polymorphism of genotype IL-6-174G/C.
Material and methods: The study covered 51 patients (34 women and 17 men, average age: 73.0+/-6.9 years) who met the NINCDS-ADRDA criteria of probable diagnosis of Alzheimer's disease and 36 patients (29 women and 7 men, average age: 73.5+/-8.2 years) without dementia features who constituted the control group. DNA was extracted from the blood by means of a QIAamp DNA Blood Mini Kit. IL-6 polymorphism was identified by the PCR method.
Results: Genotype IL-6 C/C occurred in 22.2% of patients of the control group and in 17.6% of AD patients. The genotype IL-6-174G/C occurred in 44.5% of patients of the control group and in 60.8% of patients of the AD group. The differences in genotype frequencies were not statistically significant in the examined groups (p=0.30). Differences in the frequencies of the C and G alleles in both groups (p=0.64) were not statistically significant. Analysis of the frequencies of genotypes IL-6 C/C, 174-G/C, and G/G depending on sex showed a little more frequent occurrence of IL-6 G/G and IL-6-174G/C in women suffering from AD (p=0.045).
Conclusions: This preliminary report shows no connection between polymorphism of IL-6 and the incidence of AD. The study may confirm the regional differentiation of IL-6 polymorphism in AD.