An easily detectable change in a person’s blood could signal whether they are at risk of developing leukaemia later in life.

Scientists involved in two studies discovered those with the specific mutation were 10 times more likely to be diagnosed with blood cancer.

The ‘pre malignant’ changes, they found, become more common with age - rare in those under 40 but increasing with each decade of life after that, ultimately appearing in 10 per cent of those aged over 70.

DNA tests revealed carriers of the mutations have a five per cent overall risk of being diagnosed with leukaemia or lymphoma within five years.

The changes are not present at birth, but develop as a person ages. The discovery was made independently by two research teams.

Most previous studies into blood cancers have focused on studying the DNA of cancers to identify genes that are mutated.

The new studies looked at somatic mutations – mutations that cells acquire over time as they replicate within the body.

Prof. Steven McCarroll, from Harvard Medical School, said: "People often think about disease in black and white - that there’s ‘healthy’ and there’s ‘disease’ - but in reality most disease develops gradually over months or years. These findings give us a window on these early stages in the development of blood cancer.”

Siddhartha Jaiswal, from Massachusetts General Hospital, who was first author on the other paper added: "Cancer is the end-stage of the process. "By the time a cancer has become clinically detectable it has accumulated several mutations that have evolved over many years."What we are primarily detecting here is an early, pre-malignant stage in which the cells have acquired just one initiating mutation.”

The two teams came to the same conclusion through very different routes.

In the first study, researchers investigated whether it would be possible to detect these mutations in the blood, knowing the risk of blood cancer increases with age.

They found the mutations indicated a higher risk for cancer, as well as other diseases like type 2 diabetes, heart disease and stroke - although more research needs to be done to confirm the latter findings.

In the second study, researchers were initially looking at whether the mutations increased the risk of schizophrenia.

But they discovered the mutations were concentrated in a few genes: cancer genes. They then identified a link between the mutations and an increased likelihood of blood cancers.

"The results demonstrate a way to identify high-risk cohorts - people who are at much higher than average risk of progressing to cancer,” Prof. McCarroll said, adding that in future, trials could look at how blood cancers could be prevented.

The test for mutated cells could act as a marker.

He added: "The abundance of these mutated cells could also serve as a biomarker - like LDL cholesterol is for cardiovascular disease - to test the effects of potential prevention therapies in clinical trials.”

Prof. Benjamin Ebert, who led the second study, added: "A new focus of investigation will now be to develop interventions that might decrease the likelihood that individuals with these mutations will go on to develop overt malignancies, or therapeutic strategies to decrease mortality from other conditions that may be instigated by these mutations.”

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What is leukemia?

Scientists don’t understand the exact causes of leukemia. It seems to develop from a combination of genetic and environmental factors.

Leukemia is thought to occur when some blood cells acquire mutations in their DNA. Certain abnormalities cause the cell to grow and divide more rapidly and to continue living when normal cells would die. Over time, these abnormal cells can crowd out healthy blood cells in the bone marrow, leading to fewer healthy blood cells and causing the signs and symptoms of leukemia.

How leukemia is classified

Doctors classify leukemia based on its speed of progression and the type of cells involved.Acute leukemia. In acute leukemia, the abnormal blood cells are immature blood cells (blasts).

They can’t carry out their normal work, and they multiply rapidly, so the disease worsens quickly. Acute leukemia requires aggressive, timely treatment.

Chronic leukemia. This type involves mature blood cells that replicate or accumulate slowly and can function normally for long. Some forms of chronic leukemia initially produce no early symptoms and can go unnoticed for years.