Different molecular behavior of CD 40 mutants causing hyper - IgM syndrome Running title : CD 40 deficiency as an ER - storage disease

1 “A. Nocivelli” Institute for Molecular Medicine and Pediatric Clinic, University of Brescia, 25123 Brescia, Italy 2 Medical Genetic Laboratory, S. Orsola-Malpighi Hospital, and University of Bologna, 40138 Bologna, Italy 3 Institute of Medical Technology, FI-33014 University of Tampere, Finland, and Tampere University Hospital, FI-33520 Tampere, Finland 4 Department of Pediatrics, University of Ege, 35030 Izmir, Turkey Department of Biomedical Sciences and Biotechnology, University of Brescia, 25123 Brescia, Italy 6 Children's Hospital-Boston, Division of Immunology and The Manton Center for Orphan Disease Research, The Karp Family Research Building 9th floor, One Blackfan Circle, Boston, MA 02115 § These authors share the senior authorship.