Males can pass on mitochondrial DNA
Thought to be an exclusively maternal process, in rare circumstances mtDNA can pass down the paternal line. Nick Carne reports.
Paternal transmission of mitochondrial DNA (mtDNA) may be possible, a new study suggests – contradicting the accepted view that it is passed on exclusively through maternal inheritance.
The find, made by a team led by Taosheng Huang from Cincinnati Children’s Hospital Medical Centre, and Paldeep Atwal, from Mayo Clinic Hospital, Jacksonville, both in the US, may stimulate further study of mtDNA genetics that leads to alternative treatments for mitochondrial diseases.
Writing in the journal Proceedings of the National Academy of Sciences, the researchers present evidence of biparental inheritance of mitochondrial DNA in 17 members of three unrelated multi-generation families. The findings were independently validated using multiple approaches for whole mtDNA sequencing.
“Our results suggest that, although the central dogma of maternal inheritance of mtDNA remains valid, there are some exceptional cases where paternal mtDNA could be passed to the offspring,” they write.
Mitochondria, the energy-producing organelles of cells that play a critical role in numerous cellular functions, contain their own compact genomes that are separate from the nuclear genome.
In nearly all mammals, this genome is inherited exclusively from the mother, and transmission of paternal mitochondria or mtDNA has not to date been convincingly demonstrated in humans.
The authors are not going overboard, noting that their results “will need to be brought in agreement with the fact that maternal inheritance remains absolutely dominant on an evolutionary timescale and that occasional paternal transmission events seem to have left no detectable mark on the human genetic record”.
But that does not hide the fact, they suggest, that this remains an unprecedented opportunity in the field.
“Elucidation of the molecular mechanism by which this biparental transmission occurs will expand our fundamental understanding of the process of mitochondrial inheritance and may provide an alternative approach to minimise the consequences of the transmission of pathogenic maternal mtDNA in humans,” they write.
“Whatever the mechanism of this unusual phenomenon may be, it is clear that years of research will be required to fully understand and exploit the ramifications of this discovery.”