While people may claim that they take after their mothers in appearance, temperament or character, genetically speaking, they are more like their fathers. A recent study shows that even though mammals inherit an equal amount of genetic mutations from each parent, they tend to display more of the mutations they inherited from their dads.
Genes determine the physical as well as physiological traits of an organism. Even many common diseases — such as cancer and type-2 diabetes — can be handed down from parent to child though genetics. Mammals and other animals pass down these genetic traits to their offspring through sexual reproduction. This process starts with meiosis, where the offspring inherits roughly half of its DNA from its mother and half from its father. However, even though the amount of DNA inherited from each parent is comparable, this does not necessarily mean that the genes from both parents play an equal role in determining who we are.
In a study just recently published in the journal Nature Genetics, researchers from the University of North Carolina School of Medicine worked with a population of mice from the Collaborative Cross — the most genetically diverse mouse population in the world — to analyze inherited gene expression. Scientists created the Collaborative Cross population by breeding wild type mice, meaning that the mice have phenotypes typical to those found in nature. This, the researchers state, makes the diversity of their mouse population comparable to the variation found in the human genome. In contrast, traditional lab mice are much less genetically diverse and, therefore, are generally used less in studies dealing with human diseases and the human genome.
For their study, the researchers bred three genetically diverse strains of mice that were descended from subspecies that evolved on different continents. Using a mother and a father from each of the three strains, they created nine different types of hybrid offspring. When the offspring reached adulthood, the researchers evaluated, quantitatively, how much gene expression came from the mother compared to the father by analyzing gene expression from different types of tissue. The quantitative analysis was performed on every gene in the mouse genome.
From the thousands of mouse genes that were analyzed, the researchers concluded that paternal genes play a much larger role than maternal genes. The copy of the father’s genes were more active for nearly 60 percent of its baby’s genes. This means that if an illness-causing mutation was inherited from the mother, the gene might be less expressed and the resulting disease could be less severe. Therefore, depending on the inheritance, the same mutation could lead to different consequences in different mice.
These findings are significant to studies that research human diseases with mammalian research models. Typically, when researchers create mouse models to study gene expression, they do not consider if the gene expression originates from the mother or the father, but now they may have to. If the results of this experiment carry over to humans, then it also has implications for the medical field. Knowing that there is an imbalance in the way parents’ genes affect a patient can help doctors predict and treat diseases more effectively.
