Residual -2.21e) OR = 1/0.19 = 5.26; 95%CI (1.15-25.00) c) Africa P-value = 0.00015 Std. Residual -1.99e) OR = 4.44; 95%CI (1.46-13.47) b) OR = 1/0.23 = 4.35; 95%CI (1.47-12.50) c) OR = 4.34; 95%CI (1.46-12.87) d) OR = 16.98; 95%CI (2.33-123.98) d) Asia OR = 1/16.98 = 0.06; 95%CI (0.01-0.43) d) Europe OR = 0.41; 95%CI (0.20-0.88) a) OR = 1/4.34 = 0.23; 95%CI (0.08-0.68) d) OR = 0.23; 95%CI (0.08-0.68) c) OR Tariquidar = 0.19; 95%CI (0.04-0.87) c) M. MspI Africa P-value = 0.03638e) OR = 4.42; 95%CI (1.46-13.43) b) OR = 1/0.22 = 4.55;

95%CI (1.49-14.29) c) OR = 4.51; 95%CI (1.49-13.67) d) Europe OR = 0.45; 95%CI (0.22-0.94) a) OR = 1/4.51 = 0.22; 95%CI (0.07-0.67) d) OR = 0.22; 95%CI (0.07-0.67) c) * Statistical analysis information: a) Multiple logistic regression: dependent variable Europe or non-Europe; b) Multiple logistic regression:

dependent variable Africa or non-Africa; c) Multinomial regression: reference category Europe; d) Multinomial regression: reference category Africa; e) Chi-square independence test (p-value and std. residual); Note: in multinomial regression Odds Ratio (OR) values are determined for the absence of expression. The introduction of the inverse value allows the indication of OR value for presence of expression of each MTase. A OR 95% confidence interval is presented. Discussion see more The considerable genetic diversity among strains of H. pylori [42] has already been used to discriminate between closely related human populations, that Linifanib (ABT-869) could not be discriminated by human genetic markers. H. pylori sequence analysis has the potential to distinguish short term genetic changes in human populations [43]. Most methyltransferases genes are part of restriction and modification mTOR inhibitor systems in H. pylori genome [18, 23, 44]. These genes represent about 2% of the total number of genes [18, 20, 21], a very high proportion

when compared with the mean percentage of methyltransferase (M) genes per sequenced genome in Bacteria (0.50%) [23]. The average number of R-M genes present in H. pylori sequenced genomes is 30, an extremely high value considering all sequenced bacterial genomes, with an average of 4.3 R-M systems per genome [23]. In addition to the high number of R-M systems present in H. pylori genome, which represent more than half of the strain-specific genes [45, 46], these R-M systems also present a high diversity among strains [18, 24, 25, 27–29, 47], allowing them to be used as a typing system [30, 31]. Moreover, some R-M systems are more prevalent in H. pylori than others, resulting in rare, medium, and frequent R-M systems [29, 30, 48]. The present study confirms the high number of M genes expressed per H. pylori strain, independently of its geographic origin and suggests that MTase expression is clearly associated with strain origin.