1. Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
2. Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
3. Histopathology Department, Great Ormond Street Hospital, London WC1N 3JH, UK
4. Serviço de Genética Medica, Hospital Pediatrico, Centro Hospitalar e Universitário de Coimbra, 3000-602 Coimbra, Portugal