Four tumors contained mutations that were predicted to result in early stop codons in either the ND1, ND4 or ND5 genes, all subunits of mitochondrial Complex I. Two tumors contained non-synonymous changes in Complex I subunits, one tumor contained a mutation in CO1 not predicted to change the amino acid sequence and one tumor contained a mutation affecting a tRNA gene. The gene discussed is MT-ND4; the disease is neoplasm.