Even if we inherit our mothers' physical appearance and personality, our DNA still contains more genes inherited from our fathers. That is according to a new study conducted by researchers at the University of North Carolina School of Medicine.
The research, published in the Nature Genetics journal, debunks the old myth we learned in high school that we get half of our DNA from our mothers and the other half from our fathers. Although we inherit the same amount of genetic mutations from our parents, meaning the variants of genetic sequence that make us unique, we actually "use" more of the genes that came from our dads.
"This is an exceptional new research finding that opens the door to an entirely new area of exploration in human genetics," says the study's lead author genetics professor Fernando Pardo-Manuel de Villena.
He says the results of the study are especially significant in the study of hereditary human diseases that rely on mammalian models for research, such as type-2 diabetes, heart disease, obesity, cancers, and schizophrenia. Studying parent-of-origin effects of these diseases could provide researchers were better insight on the underlying causes and in developing treatments for these problems, de Villena says.
Moreover, he says the scientific community has previously known 95 genes that are subject to parent-of-origin effect, also known as imprinted genes. The findings show there are thousands of other genes whose origin plays a role in its expression. For instance, if a particular gene of the many hundred known genes for schizophrenia comes from the father, the offspring has more chances of expressing that gene than if it came from the mother.
"Imagine that a certain kind of mutation is bad. If inherited from the mother, the gene wouldn't be expressed as much as it would be if it were inherited from the father," says de Villena. "So, the same bad mutation would have different consequences in disease if it were inherited from the mother or from the father."
To come up with the conclusion, the researchers bred three genetically-diverse strains of mice descended from ancestors found in different continents. Each strain was used as a mother and father to produce nine hybrid offspring with different types of genetic profile. The researchers then measured gene expression in the offspring mice in four different kinds of tissue, including brain tissue. For each gene, they then measured the gene expression derived from the mother and father to find an imbalance in offspring in their brain genes, which were found to be significantly more like their father's.
"We found that the vast majority of genes - around 80 percent - possessed variants that altered gene expression," says co-author James Crowley. "And this was when we discovered a new, genome-wide expression imbalance in favor of the dad in several hundred genes."
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