Although the increase in mtDNA-CN in the CC and CT genotypes was not significantly higher than that in the TT genotype in COPD patients (260.1 and 230.5 vs. 149.9; p = 0.343), there was a trend in IL13 CC and CT genotypes for mtDNA-CN was higher than TT genotype. This evidence concerns the gene IL13 and chronic obstructive pulmonary disease.