Prevalence and CCR3-T51C genotype–phenotype correlation of bronchial asthma among basic education school children: an observational study

Bronchial asthma (BA) is a chronic inflammatory disorder identified by different endotypes and phenotypes. Chemokine receptor 3 (CCR3) is one of the essential chemokine receptors that have a crucial role in asthma development by activating the migration of eosinophils through eotaxin production. We aimed to determine asthma prevalence among school children and to investigate the association between CCR3-T51C gene polymorphisms and the symptom-based clinical asthma phenotypes. This study employed a hybrid design, conducted at a single center in Egypt from 2020 to 2021, to explore the relationship between asthma, its clinical phenotypes, and the CCR3-T51C gene polymorphism. Initially, a cross-sectional analysis was performed, utilizing a modified version of the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire to determine the prevalence of asthma in a cohort of 60 children, who presented with diverse clinical phenotypes, alongside 100 healthy controls. Subsequently, in the case–control phase of the study, we focused on examining the association between asthma (and its clinical phenotypes) and the CCR3-T51C gene polymorphism. For both groups, serum immunoglobulin E (IgE) levels and eosinophil counts were assessed, and the genotypes and alleles of the CCR3-T51C gene polymorphism were identified using the polymerase chain reaction-restriction fragment length polymorphism (PCR–RFLP) technique. A total of 600 children aged (6 to 16 years old) were enrolled. Out of these, 72 children (12%) were diagnosed with bronchial asthma in the basic education schools in El Manzala City, Egypt. Also, 72 (12%) of the studied children had wheezes, and 48 (8%) had night cough. Children with asthma had significantly higher relative eosinophil count and serum IgE levels than the control group. In terms of CCR3-T51C genotypes analysis, the TT genotype was the most prevalent in both patient and control groups, with 63.3% and 64%, respectively, but the difference was not statistically significant (P > 0.05). Also, there were no significant associations between CCR3-T51C genotypes and laboratory biomarkers among cough, wheezy, and cough and wheezy groups, except for the CT genotype in the cough group that had a lower eosinophil count than the wheezy group (P = 0.04). Asthma affects 12% of the school-aged children. The CCR3-T51C genotype or allelic polymorphism frequency did not differ between asthmatics and controls; however, the TT genotype was more frequent in asthmatic children. Eosinophil count, serum IgE and gene polymorphism of CCR3-T51C appeared similar among different asthmatic phenotypes.