**The kids** are too clean! *Landmark study finds germ-free environment in first year can CAUSE Leukaemia

Childhood leukaemia is preventable and likely caused by keeping babies 
too clean according to a landmark study.
-The breakthrough found infants not in contact with bacteria in their first 
year are left vulnerable to a devastating mutation when they catch their 
first cold or flu.
-That is the new “unifying theory” for the cause of a major form of the 
biggest child cancer unveiled by the Institute of Cancer Research 
London today. Researchers summarising 30 years of research in to acute lymphoblastic leukaemia (ALL) found 5% of children are born with a “pre-leukaemia” genetic mutation.
-Only one in 100 of these will go on to develop the disease. Infants with the pre-leukaemia mutation are more at risk if not in contact with other children which share bacteria and brought up in environments that are too clean.
-This deprives these children of protective bacteria so that when they get 
their first common infection as a toddler it can trigger a second mutation 
which causes leukaemia.
-Lead author Prof Mel Greaves, one of the world’s leading leukaemia 
biologists, said: 
“I have spent more than 40 years researching childhood leukaemia.
"It has always struck me that something big was missing, a gap in our knowledge, why otherwise healthy children develop leukaemia and whether 
this cancer is preventable.
-“Infection was first suspected of causing this cancer around 100 years ago. 
The problem is not infection, the problem is lack of infection.
-"The findings relate to the major form of ALL, called Common B Precursor leukaemia, which make up 75% of cases. It offers hope of preventing the disease simply by exposing infants to “common and harmless bugs”.
-The authors analysed research from dozens of population wide studies showed spikes in numbers getting the form of blood cancer at a young age in wealthier countries but not poorer ones. As countries industrialised and became wealthier the population tends to have smaller families, become cut off from extended families and live in more sterile environments.
-The UK saw huge increases in cases between 1925 and 1950.The authors 
say other conditions such as Hodgkins Lymphoma and Type 1 diabetes could also be caused by similar mutations when children are not exposed to protective bacteria in their crucial first months.
-They identified four protective factors which lower the risk of the disease developing in children born with the “accidental” pre-leukaemia mutation.
-These were attending day care centres and socialising with other children 
in the first year, having older siblings, being breast fed and having a 
vaginal birth.

By

Martin BagotHealth And Science Correspondent

•  22 MAY 2018

https://www.mirror.co.uk/science/kids-clean-germ-free-environment-12573815
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Links to the headlines
Likely cause of childhood leukaemia discovered in prevention breakthrough   
Sky News, May 21 2018

 Ultra-clean homes could trigger childhood leukaemia, major review suggests  
The Daily Telegraph, May 21 2018

Most common childhood cancer 'partly caused by lack of infection'   
The Guardian, May 21 2018
Leukaemia may be triggered by keeping babies too clean as expert claims cases could be prevented by exposing children to germs   
Mail Online, May 21 2018
Make children play together in the dirt ‘to beat leukaemia’   
The Times (subscription required), May 22 2018
Links to the science
Greaves M. A causal mechanism for childhood acute lymphoblastic leukaemia
Nature Reviews. Published online May 21 2018