Sunday, December 27, 2009

Gene found that raises child asthma risk by half

Those pesky genes again. As it was always known to be highly heritable, this is no surprise. The claim that there are also environmental causes is mere assertion, as far as I can tell -- now that the "excess hygeine" hypothesis is looking shaky

A gene that increases the risk of childhood asthma by 50 per cent has been discovered by scientists in one of the largest studies into the disease. The discovery could lead to new treatments for the conditions which affects one million children in Britain.

Scientists in America found the gene called DEBNND1B sets off a chain reaction that causes the immune system to overreact to irritants, triggering symptoms such as difficulty breathing and wheezing. The findings are published online by the New England Journal of Medicine. Only one other gene has been found that increases the chances of developing asthma.

Lead author Dr Hakon Hakonarson, director of the Center for Applied Genomics at The Children's Hospital of Philadelphia, compared the genes of 793 children with persistent asthma to those to 1,988 children without to discover those with the disease had a variation in their genetic code.

Dr Hakonarson said: "We now know that the DENND1B gene and its protein are involved in the release of cytokines, which are signalling molecules that in this case tell the body how it should respond to foreign particles. "Many of these particles are well-known triggers of asthma. In asthma, patients have an inappropriate immune response in which they develop airway inflammation and overreaction of the airway muscle cells, referred to as airway hyperresponsiveness. "The gene mutations in DENND1B appear to lead to overproduction of cytokines that subsequently drive this oversensitive response in asthma patients." He added: "Because this gene seems to regulate many different cytokines, intervening in this pathway has great potential for treating asthma.

"Other asthma-related genes remain to be discovered, but finding a way to target this common gene variant could benefit large numbers of children if researchers can develop drugs to contain this signalling pathway. ."

Leanne Metcalf, Director of Research at Asthma UK, said: "A person’s likelihood of developing asthma is a combination of their genetic make-up and the kind of environment they are exposed to, especially in early life. "This large scale and well designed study has shed more light on the link between genetics and the overreaction of the immune system which is responsible for asthma symptoms, and opens up an exciting potential avenue for new treatments for the 1.1m children in the UK with asthma. "It is essential to remember, however, that genetics forms only one part of a much bigger picture, so further research is needed to understand exactly how genetic and environmental factors influence asthma."


Surgical cure for high blood pressure

Sounds good but one wonders what the long-term side-effects will be. Might be disastrous if applied to people where the cause is not neurological

High blood pressure increases the risk of heart disease, stroke, kidney failure and in general the higher the blood pressure, the greater the risk. LIfestyle improvements such as weight loss if necessary, exercise, stopping smoking and a low salt diet can reduce high blood pressure but many will require medication.

There are an estimated 15 million people in Britain with raised blood pressure and drugs to treat the condition are amongst the most commonly prescribed drugs.

For some people their blood pressure remains high even though they eat little salt and take medication.

In these patients the nervous system keeps sending signals from the brain to the kidneys to leave large amounts of salt in the blood which increases the volume of blood, causing a rise in pressure. The kidneys also produce hormones which cause the blood vessels to contract or dilate which also affects blood pressure.

The new procedure interferes with the signals to the kidneys by damaging the nerves carrying them.

The procedure involves passing a wire into the blood vessel in the groin and up into the main artery leading into the kidneys. From there the wire is used to make a series of tiny burns on the inside of the blood vessel which damages the nerve running along the outside of it.

The tiny burns just one millimetre across are the equivalent of snuffing a candle out between the fingers. A series of four or five burns are carried out in a spiral pattern along the inside of the artery to each kidney.

The blood vessel itself does not sustain serious damage as the blood flowing along inside it cools the burn, like running a burned finger under a tap. But the burn is deep enough to affect the nerve on the other side of the vessel.

Once the connection between the brain and kidneys is distrupted the signals to raise blood pressure should stop.

Early results show it can take between one and three months for the procedure to have an effect on blood pressure.

For some patients it will mean their blood pressure will respond to medication and for others it will mean they can reduce their dose or even stop taking them altogether.


1 comment:

John A said...

asthma-related genes

I womder where they got the idea to look? One possinility is probably a study done in California a couple of years ago. The idea there was to look for an increase in asthma linked to second-hand smoke, largely studying twins/sibs. No supportable/believable link, even statistical, was found - but there was quite a good indication of a genetic link for asthma.