This oral presentation is given by one of the co-authors of a paper, a lawyer who has a background in molecular genetics.The presentation summarises the paper by outlining the critical avoidable errors in prenatal genetic diagnostic testing that led to a successful claim for clinical negligence.Those errors impacted directly on the lives of a family affected by Fragile X Syndrome.Through revised UK guidelines these errors will indirectly (but positively) impact on the lives of other pregnant women carrying an unborn child potentially with Fragile X Syndrome.The work involved in this successful medico-legal claim required an analysis of both the screening and diagnostic tests employed by a genetic testing service in the UK.It also involved a review of the then current UK, European and US guidelines for antenatal Fragile X testing.It was discovered that (in this case) errors were made by the laboratory which could and should have been avoided.These errors falsely reassured the mother, who proceeded with the pregnancy.She gave birth to a boy who subsequently tested positive for Fragile X Syndrome.As a direct consequence of the work carried out by the legal team involved in this case the UK guidelines governing antenatal testing for Fragile X syndrome were modified, so that the prenatal testing errors that occurred in the specific circumstances of this case ought to be avoided in the future (in the UK).The modification to the guidelines brought them into line with those of the US.Surprisingly, the European guidelines remain equivocal.