British researchers have taken one step closer to developing a non-invasive prenatal test for sickle cell disease, a European conference has heard.
The new technique involves analysing cell-free foetal DNA found in the mother’s blood stream. The technical challenge of identifying foetal mutations in this way is that the unborn child’s DNA is mixed up with the mother’s own DNA. By only analysing smaller fragments of DNA, they were able to enhance the foetal contribution of the samples. Using unique molecular identifiers, a kind of molecular barcode, further reduced the error rate of their technique.
So far, the technique has only been tested on 24 pregnant women known to be carriers of the disease. In their study, presented last week at the European Society of Human Genetics (ESHG) conference in Gothenburg, Sweden, the technique led to the successful determination of the mutation status for 21 of the 24 pregnancies. Three samples gave inconclusive results.
The scientists say that further development and testing is needed before the technique is available for clinical practice.
Researcher Dr Julia van Campen, from Guy’s and St Thomas’, London, said: “We have developed a method of testing for SCD using cell-free foetal DNA - DNA from the foetus that circulates in the maternal bloodstream.
“Although cell-free foetal DNA testing is already available for some disorders, technical difficulties have hampered the development of such a test for SCD, despite it being one of the most commonly requested prenatal tests in the UK.”
Dr van Campen said the test had given better results than expected but added: “We also need to work to ensure that it can provide results rapidly enough to give women answers at the right time in their pregnancy, and that it can be performed at a cost that healthcare providers can afford.”
ESHG conference chair, Professor Joris Veltman from Newcastle University, said: “The development of non-invasive genetic tests that can be safely used during pregnancy is important to identify foetuses with severe disorders.
“These scientists have developed a novel state-of-the art genomics approach to do this for sickle cell disease in couples at risk. Their first results presented at the ESHG conference indicate that their test is very promising.”
Source: van Campen, J.C., Silcock, L., Yau, M., Daniel, Y., Ahn, J.W., Ogilvie, C.M., Mann, K., Oteng-Ntim, E. (2019) Abstract C08.5 – Non-invasive prenatal diagnosis of sickle cell disease by next generation sequencing of cell-free DNA. European Society of Human Genetics Conference 2019
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