MT-ND1 and neoplasm: A decrease in the copy number status of both NADH dehydrogenase subunit 1 (ND-1) and D-loop was noted in the tumor tissues compared with non-tumor tissues (ND-1: 1.077, 95% confidence interval: 0.904–1.249 vs 1.249, 95% confidence interval 1.133–1.366, P<0.05; D-loop: 0.933, 0.727–1.139 vs 1.164, 1.015–1.314, P<0.05; Figures 2a and b).