Sequencing of the mtDNA identified the following: (i) a disruptive complex I mutation in MGH-HCC1 (MT-ND1: m.G3745A, 60.2% heteroplasmy; the same mutation identified by our original sequencing of the patient's tumor); (ii) disruptive homoplasmic mutations in two complex I genes in NCI-HCC (MT-ND1: m.G3916A, 99.8%; MT-ND5: m.CA12417C, 99.9%); and (iii) no alterations in Nthy-ori 3-1 cells (Figs. 1B and 4A; Supplementary Table S2). Here, MT-ND5 is linked to neoplasm.