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    Is Mitochondrial DNA Only Inherited From Our Mothers?

    If you’re interested in testing your DNA, you’ve probably heard of the different ways to go about it. You can take an mtDNA test that traces your matrilineal ancestry, a Y-DNA test that traces patrilineal lines, or an autosomal DNA test that shows results from both sides of your family. 

    Largely speaking, an mtDNA (mitochondrial DNA) test focuses on the DNA you inherit from your mother. Women pass on mitochondria to their children, meaning you and your siblings, your maternal grandmother, and your maternal aunt all share the same mtDNA. For individuals who have questions about their mother’s side of the family, whether it’s about living relatives or health issues, an mtDNA test typically reveals specific and helpful insights into their maternal lineage.

    However, a recent study is calling into question how we understand mtDNA. In 2018, PNAS (Proceedings of the National Academy of Sciences of the United States of America) published a groundbreaking study that identified individuals who received mtDNA from both their mother and father. This study opens the door to the idea that the bi-parental inheritance of mitochondrial DNA is actually possible in humans. 

    Keep reading to learn more about mtDNA and how it affects your understanding of your ancestry and even your health.

    The First Individual Of mtDNA From Both Parents

    The discovery of mtDNA happened by chance, and not during a direct or specific study. A pediatrician and medical geneticist, named Taosheng Huang, was the first to make the discovery. Dr. Huang’s four-year-old patient had come to him with symptoms of fatigue and an intolerance to exercise. This led Dr. Huang to suspect the child had a mitochondrial disorder. 

    Dr. Hunag took a blood sample and sent the test to a special lab so he could gain further insight into the child’s mtDNA sequencing. The results were surprising. The child’s mtDNA showed two populations of mitochondrial genomes at a high level, suggesting that the child had received mitochondrial DNA from both his mother and father. Dr. Huang was so surprised that he assumed the results were a mistake and sent another sample for testing, only to receive the same results.

    Technically, the child’s test showed he received mtDNA from his mother and a paternal ancestor (which was passed down from his father). Other members of the patient’s family were tested and showed similar results of bi-parental inheritance patterns of their mtDNA. Thanks to Dr. Hunag’s discovery, more intensive research was to follow.

    The Considerations

    The presence of mitochondrial DNA from both parents is incredibly rare. Some plants, like mushrooms and yeast, have a biparental inheritance. However, in animals and humans, it’s mostly unheard of. In animals, the paternal mtDNA is typically destroyed once the embryo is fertilized. Some mice and a certain type of fruit fly have shown some paternal inheritance of mtDNA, though it’s not the norm and makes Dr. Hunag’s patient that much more interesting. 

    In the case of the young boy, the authors of the study suggest that the occurrence is due to a mutation in a nuclear gene that plays a role in mitochondrial elimination. If previously mtDNA was used to strictly trace maternal lineage, it calls into question how the rare case of inheritance of mtDNA from both parents affects our understanding of ancestry and how we trace it. 

    The majority of people will have accurate and exact results after testing their mtDNA in an effort to understand their matrilineal ancestry. Individuals use this information to learn more about a specific side of the family including ethnicity, migration patterns, and even important health information. 

    Researchers have identified a few more patients with mtDNA from both their mother and their father, but they remain the exception and not the rule. Understanding that some people do indeed have mitochondrial DNA from both parents enables doctors to further understand illnesses, like mitochondrial dysfunction. The more it’s studied and thus understood, the better doctors will be able to treat their patients and identify genetic issues. 


    Dr. Hunag’s discovery was so recently unveiled that it’ll take time for researchers to compile more evidence and study more cases of mitochondrial inheritance from both the mother and father.

    The research will need to look at the role of the mitochondrial genome and reevaluate its function within mtDNA inheritance. It’s possible its role was underestimated and that the genome behaves differently than previously understood. 

    This exciting new discovery may lead to new and improved insights into mitochondrial dysfunction, helping many people who suffer from it around the world. We may also gain a glimpse into how the mitochondrial genome plays a different, and perhaps larger role, in our DNA story.