CXCR4 and WHIM syndrome: mutation of CXCR4 leads to impaired receptor silencing inter alia by GRK6 and results in WHIM syndrome (papilloma-virus induced warts, hypogammaglobulinemia, bacterial infection, myelokathexis) [66]GRK6-deficiency leads to impaired chemotaxis and transepithelial migration in B and T lymphocytes [67]GRK6-deficient neutrophils showed enhanced chemotaxis but reduced mobilisation from the bone marrow to the peripheral blood circulation [68]