https://www.uptodate.com/contents/approach-to-the-adult-with-unexplained-neutropenia?search=Benign%20ethnic%20neutropenia&source=search_result&selectedTitle=1~9&usage_type=default&display_rank=1#H613862805
http://ascopubs.org/doi/full/10.1200/jco.2009.24.3881
https://www.sciencedirect.com/science/article/pii/S002221439900013X?via%3Dihub
http://www.mps.com.au/media/3304867/neutropenia_final_sfs_9_5_13.pdf
http://onlinelibrary.wiley.com/doi/10.1002/cncr.23614/epdf​

There is no obvious "threshold" ANC below which we feel compelled to look for other sources of neutropenia besides BEN. The best factor determining one's concern for another etiology is the patient's own history of infections and associated conditions, when available. Most hematologists would perform a bone marrow examination on patients with an ANC below 800 cells/microL; however, an ANC of 800 cells/microL for many years in a completely healthy individual is consistent with BEN.

Duffy antigen testing that shows the Fy(a-b-) allele