aPediatric Unit, Department of Clinical, Surgical, Diagnostic and Pediatric Sciences, University of Pavia

bPediatric Clinic, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy

Correspondence to Prof. Gian Luigi Marseglia, Department of Clinical, Surgical, Diagnostic and Pediatric Sciences, University of Pavia, Pediatric Clinic, Fondazione IRCCS Policlinico San Matteo, 27100 Pavia, Italy. Tel: +390382502818; e-mail: [email protected]