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

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 father’s 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 man’s 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 Iceland’s 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 Down’s 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 child’s 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 Michigan’s 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

NATO Exercise in Ukraine Coincided with MH-17 Shoot-down
2014 07 24
Rapid Trident was omitted from the flurry of coverage on the shoot-down MH-17. From the U.S. Army in Europe website: Rapid Trident supports interoperability among Ukraine, the United States, NATO and Partnership for Peace member nations. The exercise helps prepare participants to operate successfully in a joint, multinational, integrated environment with host-nation support from civil and governmental agencies. ...
Warning of ’imminent’ terror attack in Norway
2014 07 24
Norwegians were warned Thursday of the concrete possibility of a terror attack occurring in that country at the hands of people with connections to an extremist group in Syria. A press conference was called in Oslo, Norway on Thursday where an announcement was made of a "possible concrete threat" to national security in that country from terrorists related to an extremist ...
Judge says government can access everything in a Gmail account
2014 07 24
All your emails are belong to us. At least that’s what the latest court order from a judge in New York says. The warrant, granted on June 11, states that the government can access all the content and files contained in a Gmail account. Yes, this is a significant blow to privacy. The subject of this specific search relates to a money laundering ...
Scotland Yard Spied on Grieving Families: secret surveillance after police victim shot seven times in head ’by mistake’
2014 07 24
More terror from the ’anti-terror’ brigade. Undercover police gathered evidence on 18 grieving families By Rob Evans and Vikram Dodd | The Guardian Undercover police officers secretly gathered intelligence over two decades on 18 families fighting to get justice from the police, it was revealed on Thursday. The intelligence covering high-profile campaigns was collected between the mid-1980s and 2005, and affected grieving families ...
Air Algerie AH5017 with 116 onboard goes missing for hours, found crashed in Mali
2014 07 24
An Air Algerie flight carrying 110 passengers and six crew members has reportedly crashed in Mali after having disappeared from radar early on Thursday morning between Burkina Faso and Algeria. A French Ministry of Defense official told Fox News that the two French fighter jets located the wreckage of the plane, which had crashed in Mali. An airport official additionally confirmed ...
More News »