ARPC1B and Thrombocytopenia: WASL phenotypes (thrombocytopenia with or without small platelets), including substantial atopic diathesis, can be caused by biallelic LOF AR mutations in WAS/WASL interacting protein family member 1 (WIPF1) encoding WASP-interacting protein (WIP) and actin-related protein 2/3 complex subunit 1B (ARPC1B) [6,15].