Friday, April 06, 2012

Is autism in children down to mutation in sperm that's more common in older fathers?

The thinking here seems unclear.  If autism is caused by de novo mutations that means that the mutations are not found in the parents and it is therefore not hereditary.  But we read:  "Autism is hereditary, in that children with autistic people in their family are more likely than other children to be autistic."

To a significant extent therefore the findings below  would seem to be artifactual.  The authors studied only "families where just one child  has the condition" and even in that sample only one in 7 had de novo mutations.   So it seems that the findings concern only a very small subset of autistic cases and tell us little if anything about autism in general.  I do however agree with the view that there are  different types of  autism but whether the findings below apply to any clear phenotype of autism appears not to have been explored.  Unless they do the findings are essentially trivial

Many cases of autism are caused by faulty sperm and eggs, with older men more likely to father a child with the condition, researchers believe.

Three large-scale studies have highlighted the importance of mistakes in the DNA of eggs and sperm to the development of autism.

One in seven cases of autism in families where just one child  has the condition are caused  this way, the respected journal Nature reports.

The studies also showed sperm to contain more of these mistakes than eggs – and the older the man, the more errors linked to autism were found in his sperm.

It is thought that up to 90 per cent of a child’s risk of developing  autism is written in their genes but little is known about the many genes involved.

In order to find out more, three teams of researchers – including some from Yale and Harvard universities – scrutinised the DNA of hundreds of parents of children with autism and of the youngsters themselves. Unaffected siblings were also studied.

The projects revealed the importance of genetic flaws called ‘de novo mutations’.  We usually think of disease- causing genetic mistakes appearing in a parent’s DNA and being passed to their child.  But the de novo mutations first appear in the child’s DNA and are caused by problems with sperm or egg production.

The research team headed by the University of Washington showed sperm to be a much bigger culprit than eggs.  For every four mutations traced back to sperm, there was just one that began life in an egg.

The finding fits with previous studies that show that older fathers are slightly more likely to have an autistic child than their younger counterparts. One study found that a man aged 40 and over is almost six times more likely to have an autistic child as a man in his 20s or teens.

Pooling the results of the three studies revealed three genes to be peppered by these de novo mutations.

The scientists said that it is likely that hundreds of genes are involved in autism and their study shows the picture to be even more complex than thought.

It is hoped that unravelling the genetics will speed up both the search for new treatments for the condition and the development of diagnostic tests.

Autism, and related conditions such as Asperger’s syndrome,  affect more than one in 100 British children – ten times as many as  just 30 years ago. But, with the causes unclear, current treatment consists of managing individual symptoms, such as hyperactivity.

Stephen Sanders, who led the project headed by Yale University, said: ‘With every new gene we  discover, we learn more about potential treatments for patients with autism.’

The lead scientist on the third project, Mark Daly of Massachusetts General Hospital, said: ‘These results clearly demonstrate the potential of DNA sequencing  technology to articulate specific risk factors for autism.

‘We have only scratched the  surface but, with continued collaborative efforts, these gene  discoveries will point us towards the underlying biological roots  of autism.’


Is this the end of the cheap burger? EU diktat on low-quality meat means prices are set to soar

If there are no health concerns, I think the EU should butt out of this issue

The price of burgers, sausages and pies is to rocket because of an EU ban on low-quality meat.

From the end of this month, there will be a ban on bulking up fast food and supermarket value ranges with reconstituted mince made from scraps of beef and lamb.

The move will hit the shopping budget of already hard-pressed families and lead to more meat being wasted in abattoirs.

The Food Standards Agency, which risked a ban on the export of British meat products if it did not impose the Brussels-driven ruling, stressed that the change is not being made because of health or safety issues.

Instead, it is the result of a disagreement over the definition of the so-called ‘desinewed meat’.

But the meat-processing industry accused the FSA of ‘bowing down’ to the European Commission and warned of price rises and job losses.

Stephen Rossides, director of the British Meat Processors Association, said: ‘This is a criminal waste of a valuable food product at a time when we are being urged to reduce food wastage. Common sense has gone out of the window.

‘If economic principles apply, the cost of the burger will rise and it is going to be the less well-off who are affected at what is already a bad time.’

The row surrounds desinewed meat, or DSM.  This is meat that is left on bones and carcasses after slaughter. Rather than going to waste, it is grated off mechanically, creating a mince-like substance.

Jamie Oliver’s high-profile campaign for junk food to be banned from school canteens means DSM features less in school dinners than in the past.  But it is widely found in inexpensive meat products on sale in fast food restaurants and in supermarkets, where it is used to bulk up the meat content at low cost. The FSA sees DSM as being a different product to a second type of reconstituted meat, called mechanically separated meat, or MSM.

The higher pressures used in the MSM process means that while it is considered acceptable for chicken and pork, it is not deemed usable for beef and lamb, for fear of spreading diseases such as BSE.

However, the European Commission says DSM and MSM are one and the same.  Under this interpretation of the law, it will no longer be possible to put beef or lamb through even the gentler DSM processing.

Existing products will not be recalled but any foods that contain reconstituted beef or lamb will have to be reformulated.

The cheap desinewed meat in burgers will have to be replaced with more expensive cuts.

Chicken and pork carcasses can still undergo DSM processing but any foods they are put into will have to be clearly labelled.

Currently, DSM’s classification as meat means it counts towards the total meat content of a product and does not need to be listed separately on the label.

There are fears that the changes will push up the cost of some meat products so much that shoppers stop buying them, leading to job losses in Britain’s £6billion meat industry.

The British Meat Processors Association estimates that the total cost to the consumer and industry of the moratorium could reach £200million.

Describing the ban as ‘madness’, Mr Rossides said: ‘All this has happened at breakneck speed. The industry must be given time to adjust to any change in requirements and market circumstances in a controlled and properly managed way, in order to minimise market disruption and financial damage.

‘People are going to have to reformulate products, repackage and relabel. I don’t know that you won’t see an English sausage any more but it may be that it’s more expensive.’

The FSA said that if the dispute over classification can be resolved, the ban could be lifted. Its chief executive, Tim Smith, said the move had come ‘unexpectedly’.

The Food and Drink Federation said it supports ‘a pragmatic approach to the required changes, including a reasonable timeframe for the transition, to avoid disproportionate measures that could lead to meat being wasted, causing a significant impact on the environment and on the price and availability of meat raw material’.

A spokesman for the consumer watchdog Which? said that its research showed that shoppers want to know if they are eating desinewed meat and that clear labelling of food allows customers to make an informed choice.


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