Mitochondrial DNA mutations in human colonic crypt stem cells
J. Clin. Invest. Robert W. Taylor, et al. 112:1351 doi:10.1172/JCI19435 [Go to this article.]

Figure 3
Examples of frameshift mutations within cytochrome c oxidase structural genes associated with cytochrome c oxidase deficiency. (a) Sequencing electropherogram detailing a region of COIII containing a short, poly-C tract of six residues (nucleotides 9532–9537) amplified from a cytochrome c oxidase positive–reacting colonic crypt. (b) Sequencing of this region in an alternative cytochrome c oxidase–deficient crypt revealed a homoplasmic single nucleotide insertion (C9537ins). The frameshift induced by this insertion creates a premature stop codon predicting the synthesis of a truncated cytochrome c oxidase subunit III polypeptide of 110 amino acids and as such is likely to be the cause of the enzyme defect (20). (c) In another cytochrome c oxidase–deficient colonic crypt, we identified a single C nucleotide deletion within this poly-C tract (C9537del) present at near homoplasmic levels. Similar to the C9537ins mutation, this change also leads to the premature truncation of the cytochrome c oxidase III subunit, resulting in cytochrome c oxidase deficiency. Abbreviations for the amino acid residues are as follows:Asn, asparagine; Gln, glutamine; Gly, glycine; Ile, isoleucine; Leu, leucine; Pro, proline; Thr, threonine. Ter represents termination codon.