Ethnic and genetic causes of neutropenia: clinical and therapeutic implications.

The white blood cell count represents clinical data linked with different pathologic conditions, as well as with lifestyle. Another very important condition that affects the number of leukocytes is race and ethnic group-the geographic zone of origin. Genetic studies have identified the gene that controls the expression of the Duffy antigen receptor for chemokine (DARC), which is associated with the ethnic group to which individuals belong. The single-nucleotide polymorphism strongly associated with race is DARC rs2814778. Currently, it is the only condition that can explain the difference in white blood cell count between different ethnic groups. In a society increasingly characterized by multiracial issues, the leukopenia and/or neutropenia in ethnic groups must be known and accurately assessed clinically. Improved knowledge of this association may help in optimizing therapeutic approaches, mainly for African patients with severe diseases, cancer in particular. Recently, preclinical data have also suggested a link between the Duffy antigen and coagulation. This review also discusses the main causes of genetic neutropenia.