L S Chitty1, L Hui2, A Ghidini3, B Levy4, J Deprest5, T Van Mieghem6, D W Bianchi7. 1. London North Genomic Laboratory, Great Ormond Street NHS Foundation Trust, and Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK. 2. Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Victoria, Australia. 3. Antenatal Testing Centre, Inova Alexandria Hospital, Alexandria, VA. 4. Departments of Pathology and Cell Biology, Columbia University, New York, NY. 5. Departments of Obstetrics and Gynaecology, University Hospitals Leuven, Leuven, Belgium. 6. Department of Obstetrics and Gynaecology, Mount Sinai Hospital and University of Toronto, Toronto, Ontario, Canada. 7. Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD.