Icelandic biopharmaceutical company deCODE genetics published a major study today, giving the most detailed insight yet into how the age of parents influences mutations in their offspring, cataloging mutations occurring in a specific area in the genome.
The company used whole-genome data from 14.000 Icelanders, including 1500 sets of parents and children, to examine how sequence diversity in humans is the result of an evolving interaction between sex, age, mutation type and location in the genome.
According to deCODE founder and CEO Kári Stefánsson, the study is an important new chapter in the work to understand the human genome and how genetic diversity triggers the evolution of our species. "De novo or new mutations provide an important part of the substrate for evolution, launching a constant flow of new versions of the human genome into the environment. However, they are also believed to be responsible for the majority of cases of rare diseases of childhood. Providing a comprehensive catalog of such mutations from across an entire population is therefore not just scientifically interesting but also an important contribution to improving rare disease diagnostics."
The study shows that in about 10% of the genome, the mutations originating from mothers equal in number the ones coming from the father. An earlier study showed that the majority of mutations originate from fathers, due to sperm being constantly reproduced, as opposed to the egg cells of girls, which are all produced at once during their birth.
In an interview with MBL, Kári explained that the study reveals that mutations originating from mothers differ from those from fathers. "We located an area in the genome, which comprises over 10% it. In this area mutations originating from mothers are as many as those from the father. The mutations occur when a damage is being repaired, and a mistake happens. This 10% of the genome is especially vulnerable to these damages."
The study also reveals that these particular mutations have occurred over a very long period, as they have been found in African chimpanzees, and to some degree in gorillas but not orangutans. "This means that this particular area in the genome became more vulnerable to damages after the ancestors of orangutans and gorillas split into two species."
The results were a surprise to Kári and his team. "This means that the traits of humans that originate in these ten percent must evolve faster than others. We still haven't determined what sort of traits they are, but it's part of what we're working on right now."
New mutations are the foundation of evolution. Every individual is born with approximately 70 new mutations that aren't found in their parents. One in every ten individual, however, is born with mutations that cause diseases, which is the "price" we have to pay in order to continue to adapt to our surroundings, according to Kári.
deCODE's research has flourished in Iceland for the past decades, due to the nation's unique circumstances, such as how well documented everyone's ancestry is. This study leverages deCODE’s unique genetics resources in Iceland to build upon earlier results linking parental age and sex to variability in recombination and various types of mutation.