PADI4 Gene Polymorphism As a Risk Factor for Acute Chest Syndrome in Sickle Cell Anemia Patients

Introduction: Sickle cell anemia (SCA) is a chronic inflammatory disease with heterogeneous clinical features and the reasons for the heterogeneity of the clinical manifestations has not been fully elucidated. New mediators of the pathogenesis of SCA described recently include the formation of Neutrophil Extracellular Traps (NETs), which may contribute to the amplification of inflammation via the production of pro-inflammatory mediators. Peptidylarginine Deiminase 4 (PADI4) is a critical regulator of NETosis by mediating histone citrullination, an essential step for the generation of NETs. There appears to be a relationship between PADI4 gene polymorphisms and the pathophysiology of other inflammatory diseases in which NETosis seems to be relevant. Our aim was to investigate the association of PADI4 gene polymorphisms [rs874881(G>C), rs1748033(T>C), rs11203366(G>A), rs11203367 (T >C), rs2240340 (T>C)], which have been previously associated with increased PADI4 mRNA stability and with some clinical manifestations in cohorts of SCA patients. Methods: The study included 194 SCA patients (93 males and 101 females with mean age 33.29 ± 9.54 years) being followed up at the Hematology and Hemotherapy Foundation of Pernambuco (HEMOPE), Recife, Brazil. PADI4 gene polymorphisms were performed by Polymerase Chain Reaction (PCR) and their products were sequenced using the Big Dye Terminator Cycle Sequencing Ready Reaction Kit v3.1 (Applied Biosystems, CA, USA). These results obtained were compared with the clinical data obtained from the patients' records. Ethical approval was obtained from Ethics Committee of HEMOPE and all patients gave informed consent. Results: The frequencies of the genotypes found were as follows: rs874881 (22.2% GG, 50.5% GC, 27.3% CC); rs1748033 (17% TT, 42.3% TC, 40.7% CC); rs11203366 (21.1% GG, 50% GA, 28.9% AA); rs11203367 (20.6% TT, 49.5% TC, 29.9% CC); rs2240340 (24.7% TT, 46.4% TC, 28.9% CC). The distribution of the genotypes was in accordance with the Hardy-Weinberg equilibrium (p > 0.05). Twenty-four patients (12.4%) presented with a history of acute chest syndrome (ACS), 27 (13.9%) with stroke, 168 (86.6%) with vaso-occlusive crisis (VOC), and 81 (47.8%) with leg ulcers (LU). No association was observed between the polymorphisms studied and the history of LU, VOC and stroke in the patients (p > 0.05). However, for rs 874881 and 1748033 with the G and T alleles, respectively, were associated with a higher risk of ACS (OR: 2.96, p = 0.02 and OR: 4.75, p = 0.01, respectively). Conclusion: In the present study, we found an association between the wild type alleles (rs874881G and rs1748033T) and a history of ACS in our cohort of SCA patients. There is need for future studies on these polymorphisms in larger cohorts of SCA patients to affirm this association.