2.1 Clinical samples
In total, forty-three MPP patients (17 GMPPs and 26 SMPPs) were enrolled in this study. In which, twenty patients (10 GMPPs and 10 SMPPs) received label free proteomic analysis and twenty- three patients (7 GMPPs and 16 SMPPs) underwent ELISA test. Serum samples, collected from patients between January 2016 and January 2017 in Beijing Children’s Hospital, were stored and frozen at -80°C. Written informed consents were obtained by care givers of all children before entering the study. This study was approved by the Ethics Committee of Beijing Children’s Hospital affiliated to Capital Medical University ((No. 2017–23).