Shine the spotlight on another type of DNA – cfDNA. This stands for cell free DNA. It describes a group of Dinky Amigos living without the protection of their whole village – or cell. Foetal cfDNA (known as cffDNA) is found as small fragments in the maternal blood of a pregnant woman. It is shed from foetal cells into the maternal blood stream.
Currently an expectant mother can choose to have an ultrasound scan and blood test. This will assess risk for certain foetal abnormalities. In higher risk cases, parents may choose additional testing in the shape of chorionic villus sampling or amniocentesis. These are reliant on sampling cells within the placenta or amniotic sac. Both are invasive. Both carry a very small risk of miscarriage.
Now, there is a third tool in the samplers arsenal in the UK. Analysis of cfDNA is not invasive. It requires only a sample of blood from the mother. The cffDNA is separated from any free floating maternal cfDNA by size (foetal fragments are often shorter) and genetic analysis.
The cffDNA can then be amplified and tested. It will be used to test for chromosomal abnormalities such as Down’s Syndrome. Internal estimates suggest this will reduce the incidence of invasive testing to just 10% of current levels.
Developed over the last decade or so, cfDNA technology is not just useful for pre-natal screening.
ctDNA is cell free DNA shed by tumour cells and may offer a route to faster cancer diagnoses. This is being investigated by several research groups and can provide not only evidence of tumour, but location. Current tumour testing if often also invasive. So can ctDNA also become a force for less invasion? Let’s hope so.