ACKR1 and Balkan nephropathy: [1] This phenomenon is commonly defined as benign ethnic neutropenia (BEN), or benign familial neutropenia, and has recently been linked to the atypical chemokine receptor 1 (ACKR1) gene, previously known as the Duffy antigen-negative phenotype produced by a homozygous state of DARC (Fy −/Fy-) gene [1–3].