1. Institute of Molecular Biology and Biophysics, ETH Zurich, Swiss Federal Institute of Technology 8093 Zurich Switzerland
2. Institut de Génétique et de Biologie Moléculaire et Cellulaire, and Inserm U596 and CNRS UMR7104 67400 Illkirch France
3. Université L. Pasteur 67000 Strasbourg France
4. Institute of Human Genetics, University of Newcastle upon Tyne Newcastle upon Tyne NE1 3BZ UK
5. Laboratory of Nucleic Acid Chemistry‐EPFL 1015 Lausanne Switzerland