Children of older men have more gene abnormalities: study
2012-08-23 0:00

By Mariette le Roux | AFP

Do older fathers doom their children to genetic disease? This is the question raised by a new study that says older men produce more gene mutations in the children they sire, boosting their risk of schizophrenia and autism and possibly other diseases.

A fathers age is by far the biggest factor determining the rate of new, uninherited genetic mutations in his offspring, according to a paper published Wednesday in the journal Nature.

From a mans peak reproductive years in adolescence, the rate of new or "de novo" gene mutations triggered at conception in his children rises by about two per year, the study found.

The rate doubles every 16 years, meaning that the baby of a 36-year-old father would have twice as many new mutations than that of a 20-year-old.

"The age of the father is the most important factor to determine the number of new mutations that happen when a child is conceived," study co-author Kari Stefansson from Icelands DeCODE genetics company told AFP.

Though de novo mutations are not necessarily harmful, it can take only one change in a key gene to cause some types of disease -- and the more mutations the higher the risk.

The results from what is claimed to be the biggest-ever study of its kind suggest that disproportionate attention has been paid to the age at which women give birth.

"We have in a very unjust manner been pointing the finger at the old mother when we should have been careful when it comes to the old father. It is clearly dangerous to have an old father," said Stefansson.

Maternal age is linked to Downs syndrome and other chromosomal diseases that develop through a process that is different to the type of genetic mutation described in this study.

The mutations in the Nature report are caused by cell division during processes like sperm production.

Stefansson and a team in Iceland, Denmark and Britain sequenced the genomes of 78 parent-child trios, as well as hundreds of control subjects, looking for variants in the sequence of a childs genetic code that did not exist in the parents.

They found that the rate of increase in de novo mutations could be ascribed to the tune of 97.1 percent, "maybe entirely", to the age of the father -- an outcome that "surprised" the researchers.

The remaining 2.9 percent was ascribed to environmental factors and other random influences, Stefansson said, adding there was "no connection" between the mother and age-related increase in the rate of mutations.

The average newborn today has about 60 new small-scale mutations -- ranging from 25 in the child of a 20-year-old man to 65 in that of a 40-year-old, Alexey Kondrashov of the University of Michigans department of ecology and evolutionary biology wrote in an analysis of the study.

The number of de novo mutations ascribed to the mother always remains roughly 15, regardless of her age.

Previous research has shown a link between de novo mutations and autism and schizophrenia, and also a statistical link between the diseases and paternal age.

"Our contention is that a part of the increase in the diagnosis of autism that is being made these days is accounted for by increase in the age of the father," said Stefansson.

And he added further research is likely to show a similar link to other genetic illnesses, especially diseases of the brain.

In a comment also carried by Nature, Kondrashov said the study suggested a rethink of the advisable age to have children. It might be a "wise individual decision" for young men to cold-store their sperm for later use.

The age of new fathers in the Western world has been climbing in recent decades, and the number of first-time dads over 40 is growing. Official statistics show that in Iceland, the average age of fathers at conception rose from 27.9 in 1980 to 33 in 2011.

Contrary to de novo mutations which occur during cell division, inherited gene mutations are transferred at an equal rate by the father and mother, are more common and thus more commonly responsible for disease.

Scientists believe that both inherited and new mutations are responsible for diseases like autism and schizophrenia, but have not worked out the ratio of blame.

On the positive side, de novo gene mutations are a necessary element of human evolution, allowing us to adapt to our changing environment.


Article from: news.yahoo.com




Related Articles
Grandin on The Autism Surge
Study: Autism Linked to Industrial Food, Environment
Can Autism Really Be Diagnosed in Minutes?
Brain Imaging Could Detect Autism Risk in Infants as Young as 6 Months
Parent Training May Help Kids With Autism Behave Better
Autism Gastro Problems May Be Linked to Gut Bacteria
The Mystery of Akhenaten: Genetics or Aesthetics?
Sunburns damage your genetic code?
Gattaca - Visit to the local geneticist
Getting fetus genetic makeup from mother blood test


Latest News from our Front Page

No Jab, No Pay reforms: Religious exemptions for vaccination dumped
2015-04-20 20:03
Religious exemptions for childhood vaccinations will be scrapped to toughen Australia’s new “no jab, no pay’’ laws stripping welfare from parents who refuse to vaccinate their children. Social Services Minister Scott Morrison revealed he is dumping the last remaining exemption on the books after holding talks with religious leaders. Just a week after The Sunday Telegraph revealed Mr Morrison was scrapping exemptions ...
Inside David Lynch: An Esoteric Guide to Twin Peaks
2015-04-20 18:24
‘I learned that just beneath the surface there’s another world, and still different worlds as you dig deeper.’ – David Lynch If you’ve ever sensed the flimsy, thin veneer of what parades itself as the good ole US of A, and felt a bit like you’ve been sold a fake, then David Lynch’s Twin Peaks is a series you must see. ...
Third-gender toilet sign – now a reality in Sweden
2015-04-20 18:29
If you don’t identify yourself as a man, a woman or are officially handicapped — where should you go to relieve yourself? In Sweden, the social justice warriors have solved the problem by inventing a third-gender toilet sign. A couple of years ago, the Swedish language was introduced to a new personal pronoun, “hen“, to replace gender specific hon (she) and ...
Feminist goes crazy when compared to Swedish nationalist
2015-04-20 4:56
A picture of a media acclaimed feminist next to a young nationalist girl got real big attention in Swedish media last week. It is “hate” and “mockery” to show the difference between the two, according to the collective Swedish press. When the young nationalist Hanna Lindholm (member of the Sweden Democratic Youth) published a picture on internet, where she compared ...
Massive pollution scandal in Norwegian fjord
2015-04-20 4:53
The Norwegian government today gave the green light to one of the biggest single instances of pollution in the country's history. A new mine will dump its toxic tailings directly into the Førde fjord in the west of Norway. "It is shocking that Norway is the only country in the world allow new projects of this kind", said Lars Haltbrekken of ...
More News »