TLR9 and chronic obstructive pulmonary disease: Our findings were partially in accordance with this study, where we found that the TLR9 rs5743836 mutant (C/C) genotype and the C allele were expressed in higher frequency in exacerbated COPD patients in comparison with the stable group; therefore, this SNP is associated with a higher risk of exacerbation in COPD patients, but our comparison for the genotype (T/C) showed no significant differences between the two groups.