Gastric cancer (GC) is the second most common malignancy among men and the third in women, and therefore, an important public health problem in northern Brazil. The investigation of genetic factors related to immunological characteristics can aid the understanding of carcinogenesis in CG. The objective of the present work was investigate polymorphisms present in interleukin genes IL17G-197A, IL 17FA7488G, TNFαG-308A, IL10G-1082A, IL10C-819T e IL10C-592A, on samples of patients with gastric cancer and healthy patients without cancer. Case group was composed of 100 patients diagnosed with CG, met in the Hospital HUJBB (Pará, Brazil). Control group was composed of 100 individuals without cancer, unrelated, of the same population. The genetic material was extracted from 5 mL of peripheral blood with the DNA commercial kit from Roche, followed by quantification with the NanoDrop 1000 spectrophotometer. Analysis of the molecular polymorphisms was performed by real-time PCR with Taqman® probes. Measures of ancestry were investigated using a panel of 48 autosomal ancestry informative markers (AIMs). The proportions of ancestry of European, African and Amerindian were estimated using the software STRUCTURE v. 2.3.3. It was observed that the ethnic composition of the case group was 27% African, 42% European and 31% of Amerindian, while in the control group 21% African, 52% of European and 27% of Amerindian. In relation to the set of markers of interleukin IL-10 (IL10G-1082A, IL10C-819T, IL10C-592A), when the genotypic and haplotypic patterns were compared, it was noted that the haplotype distribution related to high expression (GCC/GCC, GCA, GCC/GCC/GTC, GCA/GCA, GCA/GTA) was more frequent in the patients with gastric cancer (P = 1,15e-11; OR = 2.630; IC 95% = 2.116-3.271). Among the individuals with the genotype related to the high production of IL-10, it was observed that the control group had more European contribution in their ancestry (P = 1e-06) while the group of patients with CG had more African contribution in their ancestry (P = 1.4e-5). Patients who presented TNF-α AA and TNF-α AG genotypes for TNF-α gene mutation presented a higher risk for development of cancer (P<0.001; OR 10.375; IC 95% 3.149-34.061). It is concluded that patients with a distribution of haplotypic markers of interleukin IL-10 (IL10G-1082A, IL10C-819T, IL10C-592A) related to a higher expression and higher contribution of African ancestry have a high risk of developing gastric cancer.
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