Abstract
Allergic asthma is the most frequently observed asthma phenotype in the
majority of individuals with asthma. Whereas, non-atopic asthma is a
phenotype with no allergic sensitization. Serotonin
(5-hydroxytryptamine, 5-HT) controls several physiological functions
through different serotoninergic receptors (5-HTR). However, the exact
role of the serotonin in pathophysiology of asthma has not been
understood clearly. Importantly, genetic, epigenetic and environmental
risk factors play a crucial role in the etiology of asthma. Evidence
suggests that psychosocial stress has been identified as one of the
environmental risk factors for the asthma development. Previously, the
5HTR2C gene rs6318 G>C variation has been associated with
HPA-mediated response to stress, blood cortisol levels, cardiovascular
diseases and psychological disorders. In addition, it has been
recognized that 5HTR2C receptor acts like an immunomodulator by
controlling the release of different inflammatory cytokines from
bronchial epithelial cells. However, there was no study found in the
literature to show the association between the 5HTR2C gene rs6318
G>C and asthma. Thus, this particular study aimed to
investigate the association between the 5HTR2C gene rs6318
G>C and allergic asthma in pediatric patients. This study
included 181 individuals, (120 control and 61 patients). Skin prick test
was performed for each patient to confirm asthma diagnosis and to
evaluate atopic status. Genotyping for the 5HTR2C was completed by
Quantitative-PCR analysis. The genotype distribution frequencies were
not in compliance with Hardy-Weinberg equilibrium for patients group
(p<0.00001, X2=28.0). Additionally, the frequency of risk
allele (allele C) was no significantly difference between two groups
(p=0.476, OR=0.785, 95%CI= 0.404-1.526). The genotypic distribution of
between atopic asthma and non-atopic asthma within patients groups were
in agreement with HWE (p<0.00001, X2= 14.130; p= 0.007,
X2=14.130, respectively). The allele frequency of the disrupting allele
C showed a statistically significance between atopic and non-atopic
asthma patients groups (p= 0.0318, OR= 3.555, 95%CI= 1.117-11.317).
Overall, this results indicated that there is an association between
5HTR2C rs6318 C variant and childhood non-atopic asthma.