So-called ‘warts, hypogammaglobulinemia, infections, and myelokathexis’ (WHIM) syndrome is a PID disorder characterized by defective and decreased neutrophils and consequent recurrent infections, mediated by dominant mutations in the human CXCR4 gene that encodes a G-protein-coupled chemokine receptor [85]. The gene discussed is CXCR4; the disease is infection.