CTLA4 and inborn error of immunity: A total of 59 children under the age of 12 were included in the study, consisting of 32 patients with primary immunodeficiencies (16 predominantly humoral and 16 combined PID such as Wiskott-Aldrich syndrome, activated PI3K-delta syndrome, ataxia telangiectasia, CTLA-4 or PMG3 deficiency) (Supplementary Table S1) and 27 patients with ITP (17 acute and 10 non-acute including 2 persistent and 8 chronic ITP).