Natural History Study for BEN

Benign ethnic neutropenia (BEN) is defined by peripheral blood absolute neutrophil count less than 1.5 x 10 (9) per liter without an increase in infections. This condition has been described in individuals of African descent. Although these individuals have normal myeloid maturation on bone marrow examinations, they appear to release fewer neutrophils into the circulation when stimulated by hydrocortisone, compared to normal controls. This suggests that there may be differences in the regulation of neutrophil release or trafficking. In the past decade, granulocyte-colony stimulating factor (G-CSF) has been widely used in a variety of clinical settings, from patients with chemotherapy-induced neutropenia to normal volunteers for peripheral blood stem cell collection. G-CSF, however, has not been used in individuals with BEN. Furthermore, gene expression in neutrophil proliferation and trafficking has not been studied in these individuals. The purpose of this study are to (1) identify individuals with BEN; (2) follow the natural history of BEN; (3) determine if there is a familial inheritance pattern; (4) characterize and compare neutrophil response to dexamethasone and G-CSF; (5) compare the pattern of neutrophil gene expression by microarray analyses; and (6) determine if mutations are present at the DNA level to account for gene expression pattern differences in individuals of African descent with and without BEN at baseline, post dexamethasone, and post G-CSF stimulation.