Length heteroplasmy of the polyC-polyT-polyC stretch in the dog mtDNA control region

Abstract

Previously, the mitochondrial control region of 214 Belgian dogs was sequenced. Analysis of this data indicated length heteroplasmy of the polyT stretch in the polyC-polyT-polyC stretch from positions 16661 to 16674. Nine polyC-polyT-polyC haplotype combinations were observed, consisting of seven major haplotypes (highest signal intensity) combined with minor haplotypes (lower signal intensity) one T shorter than the major haplotype in all but three dogs. The longer the polyT stretch, the smaller was the difference in signal intensity between the major and minor haplotype peaks. Additional sequencing, cloning, and PCR trap experiments were performed to further study the intra-individual variation of this mitochondrial DNA (mtDNA) region. Cloning experiments demonstrated that the proportion of clones displaying the minor haplotypes also increased with the length of the polyT stretch. Clone amplification showed that in vitro polymerase errors might contribute to the length heteroplasmy of polyT stretches with at least 10 Ts. Although major and minor polyC-polyT-polyC haplotypes did not differ intra-individually within and between tissues in this study, interpretation of polyT stretch variation should be handled with care in forensic casework.

Defect of the mitochondrial DNA hypervariable region as a risk factor for canine mammary tumour

“…This phenomenon is often observed in the control region of mtDNA. In dogs, length heteroplasmy has been identified in the polyT fragment of the Polyc‐polyT‐Polyc stretch from position m.16661 to m.16674 . Therefore, the identification of the length heteroplasmy in this study seems noteworthy.…”

Mitochondrial genetic variation and gout in Māori and Pacific people living in Aotearoa New Zealand

“…The 16189C variant contributes to a poly-cytosine tract between 16184 and 16193. There is accumulating evidence that homo-nucleotide tracts such as this may induce polymerase slippage—something that has certainly been observed in vitro, but which may also be occurring in vivo 47. Because the dataset reported here had the derived C allele at position 16189 occurring at a frequency of 0.96, the 16189C variant was not included in the gout association analysis.…”