21 March 2016
ByAppeared in BioNews 844
Scientists say they have been able to detect multiple diseases, including pancreatic cancer, multiple sclerosis and type 1 diabetes, by analysing fragments of DNA in the bloodstream.
They hope to develop a new type of blood test that can detect these diseases at a very early stage, leading to earlier treatment and better prognoses.
'Our work demonstrates that the tissue origins of circulating DNA can be measured in humans. This represents a new method for sensitive detection of cell death in specific tissues, and an exciting approach for diagnostic medicine,' said study co-author Dr Ruth Shemer of the Hebrew University of Jerusalem in Israel.
Researchers investigated cell-free DNA (cfDNA) in blood taken from over 300 patients suffering from a variety of diseases, and were able to identify the type of disease patients were suffering from.
It has been known for some time that dying cells release fragmented DNA into the bloodstream. But as the DNA in all cells of the human body is identical it had not previously been possible to identify which tissue the DNA had come from.
However, the methylation patterns vary between tissues – with different genes being turned on or off in different tissues. Using these patterns the researchers were able to distinguish different cell types.
They were able to detect cfDNA of oligodendrocytes – the brain cells destroyed multiple sclerosis – in the bloodstream of 14 out of 19 patients with the disease. Other diseases, such as pancreatitis and type I diabetes, similar levels of detectable cfDNA.
The researchers were also able to distinguish pancreatic cancer from pancreatitis, by incorporating a test for a cancer mutation alongside methylation pattern recognition. Two other research groups have also reported positive preliminary results in cancer detection.
Prior to this work it had not been possible to measure cell death non-invasively. The researchers now hope that this approach could be adapted to identify cfDNA derived from any cell type in the body.
'In the long run, we envision a new type of blood test aimed at the sensitive detection of tissue damage, even without a priori suspicion of disease in a specific organ. We believe that such a tool will have broad utility in diagnostic medicine and in the study of human biology', said Professor Benjamin Glaser, head of endocrinology at Hadassah Medical Center and a lead author of the study.
Immunobiologist Professor Kevan Herold of Yale University, who was not involved in the study, told Science that the work bodes well for developing a cfDNA test that could be used to screen people at high risk for type 1 diabetes before their pancreas is so damaged that blood sugar levels rise. 'The hope is that we could intervene at an early stage and try to prevent progression,' he said.