Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome is an autosomal dominant inborn error of immunity caused by pathogenic gain-of-function variants in CXC chemokine receptor 4 (CXCR4) (HGNC:2561) with an estimated incidence of 0.2 per million births.1–3 CXCR4 variants that result in hyperactive signaling from this receptor cause retention of immune cells in the bone marrow with peripheral neutropenia and lymphopenia, termed myelokathexis.2 Despite peripheral cytopenias, individuals with WHIM syndrome do not commonly suffer from invasive infections characteristic of other chronic neutropenic disorders.