Researchers have uncovered rare cases of male mtDNA transmitted to offspring

A team of researchers from the United States, China and Taiwan has uncovered rare cases of fathers who have transmitted mitochondrial DNA (mtDNA) to their offspring. In their article published in Proceedings of the National Academy of Sciences, the group describes how they discovered one case, then found it in others.

Mitochondria are organelles that reside in every human cell – their function is to produce energy. Mitochondria have the particularity of possessing a type of DNA distinct from that located in the nucleus, called quite judiciously mitochondrial DNA. Previous research has shown that mtDNA in spermatozoa is destroyed when an egg is fertilized. Thus, the offspring inherit only maternal mtDNA. Due to the uniqueness of mtDNA, it has been widely used to study the genetic history of humans and other animals.

Most people learn at school that the mtDNA is passed from the mother to her offspring, but there seem to be rare exceptions. In 2002, for example, a team of researchers reported finding a case in which a man had mtDNA from both parents. In this new effort, the researchers found 17 other cases, all belonging to three independent family trees.

The researchers indicated that they were interested in the case of a man suffering from mutations believed to be mitochondria. Subsequent tests on his mtDNA and that of his parents revealed that he had inherited the mtDNA from each one of them. Intrigued, researchers began to be interested in other patients with diseases due to mitochondrial mutations. In total, the researchers found 17 cases of mtDNA patients from both parents. They also report that their results were validated independently and that the use of several types of sequencing guaranteed the validity of their results.

The researchers suggest that it is likely that some males carry genetic mutations that prevent the destruction of their mRNA, allowing them to remain active in the mitochondria of their offspring, along with the mother's mRNA. They further suggest that their findings may prove useful in the fight against certain types of mitochondrial diseases.

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More information:
Shiyu Luo et al. Biparental inheritance of mitochondrial DNA in humans, Proceedings of the National Academy of Sciences (2018). DOI: 10.1073 / pnas.1810946115