Genetic factors behind the tragic deaths of children struck down by meningitis have been identified for the first time.
Experts hope the breakthrough will boost 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 lives around the world.
Scientists scoured the genetic codes of more than 6,000 people for clues to why certain individuals are more vulnerable to attacks by meningococcal meningitis than others.
They found evidence that genetics plays a key role in the way the body responds to the infection.
Scientists looked at the genetic makeup 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, from the Department of Paediatrics at 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 meningococcal meningitis. Our study set out to understand what causes this small group of people to become very ill whilst others remain immune. Our findings provide the strongest evidence so far that there are genetic factors that lead to people developing meningitis."