The consequence of these multiple ways of mixing and assorting mtDNA both within a single mitochondrion and the collected mitochondria of the cell as a whole leads to the concepts of homoplasmy
(where all mitochondrial genomes in a cell or organism are of the same sequence) and heteroplasmy (where two or even more mitochondrial genome types can be present simultaneously in an organism).
91) More studies are needed to understand the role of heteroplasmy in sperm mtDNA of infertile men, where homoplasmy mutant mtDNA has also been reported in OA infertile patients.
Another recent study (92) from India showed a novel missense mutation (C11994T) in the ND4 gene of oligoasthenozoospermic samples and it has been proposed that the wild type allele had totally replaced by the mutant allele over several generation in the maternal lineage leading to the mutantDNA homoplasmy.
A possible explanation for mutant mtDNA homoplasmy in tumor cells is that mutant mtDNAs might alter mitochondrially mediated apoptotic pathways to escape cell death.
change Gene B1T 5 G3010A RNR2 B1T 7 A4769G ND2 B1T 11 A9448G CO3 B1T 16 A15326G Cyt-b S2T 3 C476T RNR1 S2T 8 G5979A CO1 S2T 10 C7956T CO2 S2T 12 C10527T ND4L S2T 13 C12465T ND5 S2T 1 C16520T D-loop B8T 2 A263G R sequence B8T 14 A13032G ND5 B8T 16 C15409T Cyt-b B8T 17 A16051G D-loop S3T 6 C3992T ND1 S3T 7 T5004C ND2 S3T 10 G8269A CO2 S3T 11 G9123A ATP6 S3T 12 A10044G tG S3T 16 A15326G Cyt-b Detected in Detected in Homoplasmy or Tumor uniplex?
A complete homoplasmy
(the same mtDNA sequence) for each of these copies is unlikely because of the immense amounts of mtDNA present in the body.
Over multiple cell divisions, the proportion drifts toward either predominantly mutant or wild-type mitochondrial DNAs, leading to homoplasmy
Once the mutation was identified by sequencing, a second method such as PCR/allele-specific oligonucleotide dot blot or PCR/ restriction fragment length polymorphism analysis was used to confirm the status of homoplasmy
or heteroplasmy (13,14).