Not all DNA is the same, and science has long claimed that not all types of DNA are sent down…
Not all DNA is the same, and science has long claimed that not all types of DNA are sent down from both your mother and your dad. But it seems that the time has come to rewrite the textbooks.
While most of our DNA is within the nucleus of the cell, part of our genetic code is stored within mitochondria, the so-called “powerhouse”. The conventional perception is that this mitochondrial DNA (or mtDNA) is only inherited from mothers, but new evidence indicates that this is not the case at all.
A new study led by geneticist Taosheng Huang from the Cincinnati Children‘s Hospital Medical Center shows human mitochondrial DNA can be paternal inherited, in a landmark case that began with treatment of a sick four year old boy.
The child, who showed signs of fatigue, muscle aches and other symptoms, was evaluated by a doctor and tested to see if he had a mitochondrial disorder.
When Huang ran the tests ̵
1; and then ran them back to be safe – he could not understand the results that came back.
“It’s impossible,” he told NOVA Next.
The reason why Huang was so shocked was that the boy’s results showed a mixture – called heteroplasmia – in its mitochondrial DNA, consisting of more than just mother contributions.
Although there are signs of father’s mtDNA transmission in other species, the phenomenon of people has been discussed, but has never been shown before.
“This increases the entire field based on genetics,” ecolog Trevor Branch of the University of Washington, who was not involved in research, tweeted about the discovery.
When the boy’s sisters showed evidence of the same heteroplasmia, Huang and other researchers analyzed the children’s mtDNA mother, who also showed the same blend.
This led the team to analyze mother’s parents mtDNA, and finally found that the mother’s mtDNA came from a 60/40 split from her mother and dad.
“Our findings indicate that although the central dogma of mtDNA’s mother’s life is still valid, there are some exceptional cases where paternal mtDNA could be transmitted to the offspring,” explains the authors of his paper.  But while these cases may be exceptional , they are not necessarily as rare as scientists may have believed.
In total, the researchers identified three unrelated multiple generation families who showed a high level of mtDNA heteroplasm – ranging from 24 to 76 percent – over 17 separate individuals.
Previously, two separate case reports that occurred early in the century suggested that biparental mtDNA transmission could be possible, but for 16 years no other evidence was found.
Now we know that the results were not isolated and as the sequencing technique is progressively more advanced it gives us a better tool to understand what’s happening here and how common paternal mtDNA over management really is.
“This is a truly pioneering discovery”, biologist Xinnan Wang of Stanford University, who was not involved in research, told NOVA Next.
“It can open a whole new field … and change how we look for the cause of [certain mitochondrial] diseases.”
The researchers say that the strength of the previous opinion – only material transfer was possible – could have caused many instances of grant transmission before being overlooked as technical errors.
Be as they can suggest they are “clear and provocative”. Evidence should now begin a wider assessment of mtDNA opportunities, even though mammalian transmission remains the norm. “
” It is clear that these results must be come in line with the fact that the inheritance of the mother is still absolutely dominant in an evolutionary schedule and the temporary father’s transmission events appear to have left no detectable mark on the human genetic record, the team writes.
“This is still an unprecedented opportunity on the field.”
The results are reported in PNAS .