Meningitis deaths linked to genetic make up
Published 09/08/2010 | 05:00
GENETIC factors behind the deaths of children from meningitis have been identified for the first time.
Experts hope the breakthrough will boost the development of vaccines that protect against the deadliest strain of meningitis bacteria.
Currently, there is no vaccine for the group B strain, which each year claims thousands of live around the world.
Scientists scoured the genetic codes of more than 6,000 people for clues as to why certain individuals are more vulnerable than others to attacks by meningococcal meningitis.
They found evidence that genetics plays a key role in the way the body responds to the infection.
It was already known that most people carry the bugs in their throats without ever succumbing to the disease. But occasionally, the bacteria strike with devastating force, leading to death in up to one in 10 cases.
Most victims are children under five and teenagers. Progress of the infection can be lightning fast, with patients becoming critically ill within hours.
Meningitis affects the layers of membranous tissue that surround the brain, but sometimes the infection leads to septicaemia, a highly dangerous form of blood poisoning.
Although people can be immunised against some types of meningococcal bacteria, scientists have been unable to develop a vaccine against the group B strain.
The new research, led by teams in London and Singapore, involved the biggest-ever genetic study of bacterial meningitis.
Scientists looked at the genetic make-up of 1,500 people from the UK, Holland, Austria and Spain who had developed meningococcal meningitis.
Their DNA was compared with that of more than 5,000 individuals who had never suffered a bacterial-meningitis infection.
The researchers focused on half-a-million genetic sites which commonly vary between individuals looking for differences between the two groups.
The findings, published in the journal 'Nature Genetics', showed that susceptible people had alterations in their DNA around genes for 'factor H' proteins. These regulate a bacteria-fighting part of the immune system and prevent it damaging the body's own cells.
Meningococcal bacteria are able to 'hijack' factor H and use it to fly into the body without being attacked.
Professor Michael Levin of Imperial College London, who led the research, said: "Although most of us have carried the meningitis bacteria at some point, only around one in 40,000 people develop menin-gococcal meningitis.
"Our study set out to understand what causes this small group to become very ill whilst others remain immune.
"Our findings provide the strongest evidence so far that genetic factors lead to people developing meningitis."