Décrypthon is a project which uses grid computing resources to contribute to medical research. The word is a portmanteau of the French word "décrypter" (to decipher) and "telethon". Description Décrypthon is a technology platform providing the computational power required to process complex data in biology. It allows, through technologies called "grids", to gather (in a grid) the capacity of several supercomputers (500 Gflop) installed by IBM in 6 French universities (Bordeaux 1, Lille 1, Paris 6 Jussieu, ENS Lyon, Crihan in Rouen, Orsay) and/or individual personal computers via the World Community Grid, itself a BOINC project. A dozen scientific projects selected through a call for tenders have been completed under the Décrypthon program. History During the 2001 French Telethon, the AFM ("Association française contre les myopathies" / "French Association Against Myopathy") and IBM launched a call to mobilize Internet users: "Make your unused computer time available to research". Objective: Accomplish the first proteome mapping: all the proteins/molecules produced by cells. This scientific, technological and human challenge was brilliantly taken up: 75,000 Internet users mobilized, billions of complex calculations performed, 550,000 proteins mapped. It is a library for comparing proteins from different species of living organisms (animal, plant, human). It contains nearly 2.2 million files divided into 17,000 directories. All this in less than two months whereas it would have taken more than 1,170 years to achieve with a single computer. Each computer contributed about 133 hours, or more than 10 million hours of calculations in total. Twenty-one IBM servers coordinated the solutions and data throughout the operation. Following this success, in 2003 the AFM launched a call for tenders to promote the use of this knowledge base. Four projects were selected: A project was proposed by two teams from Commissariat à l'Energie Atomique (CEA, Commission for Atomic Energy) Department of Life Sciences at Saclay (S Zinn-Justin and R Guérois) in association with A Poupon, from the National Center of Scientific Research (Centre Nationale de la recherche scientifique ou CNRS), Laboratory of yeast structural genomics from the University of Orsay. This project aimed to study the relationships between structure and function of proteins that reduce the risk of genetic abnormalities in humans and yeast. Three other teams from the IGBMC (Institut de génétique et de biologie moléculaire et cellulaire, Genomics Institute of molecular and cellular biology) in Illkirch, J Laporte and J-L Mandel, A Pujol and J-L Mandel, G Bey, F