Darren K Griffin, PhD, DSc, FRSA, FRSB, FRCPath, is Professor of Genetics at the School of Biosciences, University of Kent, Canterbury, UK, President of the International Chromosome and Genome Society, and Director of the Centre for Interdisciplinary Studies of Reproduction. Gary Harton, PhD, is Global Director of Market Development PGD for Perkin-Elmer Inc., Waltham, MA, teacher at Eastern Virginia Medical School, Norfolk, VA, and at Bryant University, Smithfield, RI, USA: he has worked for over 20 years in both laboratory and clinical management in the IVF field and has served on a number of international committees including the ESHRE PGD Consortium and the UK Steering Committee for External Quality Assessment.