MT-CO3 and idiopathic pulmonary fibrosis: IPF patients had more non-synonymous (NS) variants (substitution/deletion/insertion) in mitochondrial COX3 gene (coding for subunit 3 of complex IV of the respiratory chain), and more mitochondrial tRNA variants located in the anticodon (AC) stem, AC loop, variable loop, T-arm, and T-loop of the tRNA clover-leaf structure in PBLs than the control group.