Association between Fc-Gamma Receptor Polymorphisms and Autoimmune Neutropenia in Early Childhood in Danish Patients

Background Copy number variation (CNV) in the genome is difficult to analyze with standard genotyping methods. CNV in the Fcγ receptor region (FCGR) is associated with risk of autoimmune disease. Genetic variation in Fc-gamma coding genes is also abundant, and several functional polymorphisms are described. Autoimmune neutropenia (AIN) primarily affects children under the age of five but can also affect adults. The disease is caused by autoantibodies reactive to neutrophil surface antigens, primarily the FCGR3B receptor. We investigated the association between common SNPs and CNV in Fcγ receptors and AIN.

Aims Establish the association between CNV and genetic variation in Fc-gamma receptor coding genes in Danish patients.

Methods 127 Danish AIN cases were compared with 610 healthy and unrelated Danish blood donors for FCGR2A-H166R, and with 919 Caucasians (1) for FCGR3A-V158F, FCGR2B-B2.4, FCGR2B-I232T and CNV. Molecular determination of copy number and genotypes was determined using Multiplex Ligation Probe Assay (MLPA) with the following SALSA MLPA probemixes: P110-C1 FCGR mix 1 and P111-C1 FCGR mix 2. Statistical analysis was performed with Fisher Exact test.

Results The polymorphisms FCGR2A-166H, FCGR3A-158F, FCGR2B-232I were statistically significantly associated with a higher risk of AIN (Table 1). The presence of a FCGR2B-2B.4 promoter haplotype was associated with a significantly lower risk of AIN (OR=0.5). There was not observed a difference in the distribution of CNV for the Fc-gamma receptor genes (data not shown).

Summary/Conclusion In our Danish cohort, we report an association between AIN and polymorphisms in Fc-gamma receptor 2A, 3A and 2B, indicating a significance of other Fc-gamma receptors than FCGR3B. We do not observe a difference in the distribution of CNV of the Fc-gamma receptor genes.

1) Nagelkerke SQ, Tacke CE, Breunis WB, Tanck MWT, Geissler J, Png E, Hoang LT, van der Heijden J, Naim ANM, Yeung RSM, Levin ML, Wright VJ, Burgner DP, Ponsonby A-L, Ellis JA, Cimaz R, Shimizu C, Burns JC, Fijnvandraat K, van der Schoot CE, van den Berg TK, de Boer M, Davila S, Hibberd ML,Kuijpers TW and the International Kawasaki Disease Genetics Consortium (2019) Extensive Ethnic Variation and Linkage Disequilibrium at the CGR2/3 Locus: Different Genetic Associations Revealed in Kawasaki Disease. Front. Immunol. 10:185. doi: 10.3389/fimmu.2019.00185

Glenthøj:Novo Nordisk: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sanofi: Research Funding; Celgene: Consultancy; Saniona: Research Funding; Pharmacosmos: Consultancy, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees.