Life immitates art: New process allows babies to be tested for 3500 genetic defects in the womb

 

June 7, 2012 – TECH – A team has been able to predict the whole genetic code of a foetus by taking a blood sample from a woman who was 18 weeks pregnant, and a swab of saliva from the father. They believe that, in time, the test will become widely available, enabling doctors to screen unborn babies for some 3,500 genetic disorders. At the moment the only genetic disorder routinely tested for on the NHS is Down’s syndrome. This is a large-scale genetic defect caused by having an extra copy of a bundle of DNA, called a chromosome. Other such faults are sometimes tested for, but usually only when there is a risk of inheriting them from a parent. By contrast, the scientists say their new test would identify far more conditions, caused by genetic errors. However, they warned it raised “many ethical questions” because the results could be used as a basis for abortion. The American scientists were able to map the baby’s genetic code principally from tiny traces free-floating DNA, which makes its way into the mother’s blood. Blood sample DNA from the mother was also studied as well as DNA extracted from the father’s saliva. Fitting pieces of the genetic jigsaw together, scientists in the US were able to reconstruct the entire genetic code of an unborn baby boy. They were then able to see what spontaneous genetic mutations had arisen. Such natural mutations – called ‘de novo’ mutations – are responsible for the majority of genetic defects. By checking their prediction of the baby’s genetic code with actual DNA taken after the birth, the team from the University of Washington in Seattle found they were able to identify 39 of 44 such mutations in the child. Dr Jay Shendure, the lead scientist, said: “This work opens up the possibility that we will be able to scan the whole genome of the foetus for more than 3,000 single-gene disorders through a single, non-invasive test.” In the future, a more refined and less costly version of the procedure could make pre-natal genetic testing far more comprehensive than it is now, the scientists say. –The Telegraph

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