CXCR4 and HIV-1 infection: Deletion of Cxcl12 or Cxcr4 in mice results in a variety of developmental abnormalities and embryonic death (Table S1), whereas genetic variants of CXCL12 or CXCR4 are associated with resistance to HIV-1 infection and the development of WHIM (warts, hypogammaglobulinemia, infections, and myelokathexis) syndrome (Table S2) [330].