To this end, we used two CXCR4 mutants with an N-terminal T7-tag and deletions of the last 10 and 17 C-terminal residues (CXCR4-Δ10, CXCR4-Δ17), which correspond to WHIM syndrome-associated mutations in the human CXCR4 gene [29], [39]. The gene discussed is CXCR4; the disease is WHIM syndrome.