Rare Bi-parental Mitochondrial inheritance in Humans
The energy-producing structures “Mitochondria” found in every cell of our body contains its own compact genome, which is separate from the nuclear genome. In nearly all mammals, this mitochondrial genome is inherited exclusively from the mother, and transmission of paternal mitochondria or mitochondrial DNA (mtDNA) has not been convincingly demonstrated in humans. But doctors in the US have now identified more than a 12 individuals in three different families who have inherited mitochondria from both parents which is very rare.
It appears that these individuals are an exceptional and rare case, because these families developed mutations that disrupt the usual mechanism that normally prevents a father’s mitochondria being passed to his next generation. Father’s mitochondria enters the egg and marked with a chemical tag that marks them for “destruction”, so usually all the mitochondria are transferred from mothers.
However, in 2002 one case was identified in which the cells of one man contained a mixture of mitochondria from his father and mother.
But no such case reported since then and many questioned the correctness of 2002 case.
Mitochondrial diseases or disorders results from failures of the mitochondria, which are specialized energy packets present in every cell of the body (except red blood cells). Mitochondria are responsible for generating more than 90% of the energy needed by the organic body to sustain life and support other organ level functionality. When they fail, less and less energy is generated within the cell. Cell injury and even cell death follow. If this process is repeated throughout the body, whole organ systems begin to fail. The parts of the body, such as the heart, brain, muscles and lungs, requiring the greatest amounts of energy are the most affected. Mitochondrial disease is difficult to diagnose, because it affects each individual differently. Symptoms can include seizures, strokes, severe developmental delays, inability to walk, talk, see, and digest food combined with a host of other complications. If three or more organ systems are involved, mitochondrial disease should be suspected.
First case was identified and diagnosed because he was suffering from fatigue and muscle pain, which was suspected to be caused by mitochondrial mutations. It was later observed that he inherited mitochondria from both of his parents. And a new mutation also has arisen in the paternal mitochondria.
Later studies was done and it was observed that other members of the same family also has mixture of mitochondria from both parents. Other patients was also being studied, and two more families identified with mitochondrial inheritance from both parents.
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Research paper published in a journal (reference below):
