It is reported that almost all cases of WHIM syndrome are caused by mutations distributed in the cytoplasmic C-terminus of cysteine-X-cysteine chemokine receptor 4 (CXCR4), which contains eighteen potential serine/threonine phosphorylation sites [11], and six of them are phosphorylated by various kinases such as G protein-coupled receptor kinases (GRKs) and protein kinase C (PKC) upon stimulation with the ligand stromal-derived factor (SDF1, also known as CXCL12). This evidence concerns the gene CXCR4 and WHIM syndrome.