https://www.selleckchem.com/products/jib-04.html Autoimmune neutropenia of infancy (AIN) is a frequent cause of neutropenia in children. The disease is caused by antibodies against epitopes on the immunoglobulin G (IgG) Fc receptor type 3b (FcγIIIb). We investigated the possible association of human neutrophil antigens (HNA), human leukocyte antigen (HLA)-DR, and HLA-DQ alleles with AIN and the association of these genotypes with the presence of autoantibodies. Eighty AIN cases with a median age of 13.5months were included. Controls were healthy unrelated Danish blood donors. Anti-HNA-1a autoantibodies were detected using a flow cytometric granulocyte immunofluorescence test (Flow-GIFT) with phenotyped donor cells for detection of antibody specificity. Molecular determination of HNA genotypes was determined using real-time polymerase chain reaction (q-PCR). High-resolution HLA-DRB1 and HLA-DQB1 were determined by next-generation sequencing. Antibodies against HNA-1a were detected in 51% (n=41) of AIN patients, and anti-HNA-1b was detected in 3% (n=2) of cases. In 46% of cases, the antibodies were anti-FcγIIIb-reactive. FCGR3B*01+,*02-,*03- was more common (odds ratio, 6.70; P<.0001), and FCGR3B*01-,*02+,*03- was less common (odds ratio, 0.30; P<.0001) among AIN cases. HNA-1a antibodies were significantly more frequent among AIN cases with the FCGR3B*01+,*02-,*03- genotype (odds ratio, 3.86; P<.007). The HLA-DRB1*14 - HLA-DQB1*0503 haplotype was significantly more common (odds ratio, 7.44; P<.0001) in AIN patients. The HLA haplotype HLA-DRB1*14 - DQB1*0503 is associated with Danish AIN cases. Among Danish AIN patients, anti-HNA-1a is the most common autoantibody, and the antibody is more common in cases with the FCGR3B*01+,*02-,*03- genotype. The HLA haplotype HLA-DRB1*14 - DQB1*0503 is associated with Danish AIN cases. Among Danish AIN patients, anti-HNA-1a is the most common autoantibody, and the antibody is more common in cases with the FCGR3B*01+,*02-,*03- genoty