It's Dad's fault: mice 'use' genetic mutations inherited from fathers more

The idea that all of us - men and women - are chips
off the paternal block has been given some scientific credence by a study in mice.

Like all mammals, the lab mice inherited two copies
of almost all of their genes - one copy
from each parent. But analysis revealed that when the mice carried two
different variants of the same gene, the variant inherited from the father was
the one more likely to be 'used', or expressed as a protein.

Dr James Crowley, of the University
of North Carolina, USA, the first author of the study, said the research had
unearthed 'a new, genome-wide expression imbalance in favour of the dad in
several hundred genes'.

In particular, Dr Crowley added,
'this imbalance resulted in offspring whose brain gene expression was
significantly more like their father's'.

For the study, published in Nature
Genetics, researchers first selected three genetically distinct mouse strains. Male
rats and female rats from each strain mated with each other to create nine
hybrid species.

When the offspring mice reached adulthood, the
researchers measured gene expression in four different kinds of tissue. They
found that around 80 percent of mice's genes possessed variants that altered
gene expression. For each of those genes, they worked out whether the
paternally or maternally inherited variants were more likely to be expressed.

The researchers say that the effect they observed was
occurring in addition to the already known phenomenon of imprinting, where one
copy of a gene is effectively silenced.

The discovery may have implications for research
into medical conditions like heart disease, diabetes, and many
neurodegenerative disorders, which have a genetic component but where
the genetics is more complex than just pinpointing just one or two faulty genes.

'We now know that
mammals express more genetic variance from the father,' said Professor Fernando
Pardo-Manuel de Villena, who led the study. 'So 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. So, the
same bad mutation would have different consequences in disease if it were
inherited from the mother or from the father.'

Speaking to USA Today, Professor Nicholas
Katsanis of Duke University, who was not involved in the study, said the
research 'serves as a very good reminder that just when we thought we
understood the genome we don't'.

The inference that we are all little more like our fathers than our
mothers has also sparked public imagination. One comment on MailOnline observes that the idea that nature prioritises the father's
genetic variations 'makes sense' as 'sexual reproduction provides variety and males
suffer more "churn" (death-based selection) in the population than
females (i.e. they are more likely to carry adaptive advantage in traits)'.