PURPOSE: to study the polymorphism of the GSTP1 in Egyptian patients suffering from bronchial asthma and comparing them with control subjects to examine the hypothesis that polymorphism in the GSTP1 locus is associated with asthma and related phenotypes
METHODS: Fifty patients with bronchial asthma and fifty normal control subjects were subjected to asthma questionnaire, spirometric studies, conventional PCR with enzyme digestion to determine GSTP1 genotype, serum IgE measurement and eosinophilic count
RESULTS: Seventeen patients (34%) had mild asthma, 17 patients (34%) had moderate asthma and 16 patients (32%) had severe asthma. As regards FEV1% predicted; 16 patients (32%) had FEV1≥ 80% predicted and 34 patients (68%) had FEV1 < 80% predicted. Using Alw261 restriction enzyme analysis for the GSTP1 polymorphism three genotypes were found: Ile/Ile, Ile/Val, and Val /Val. The genotype distributions for GSTP1 gene polymorphism in bronchial asthma subjects and controls showed no significant difference. The allele frequencies of the Val and Ile in patients with asthma were 0.31 and 0.69 respectively whereas in controls we report frequencies of 0.41 and 0.59 for Val and Ile alleles respectively with no significant difference between both groups (p=0.141). Both patients and controls were found to be in Hardy-Weinberg equilibrium (p= 0.233 and 0.159 respectively). Presence of the Val /Val genotype did not confer a decreased risk for developing bronchial asthma (OR = 0.34, 95% CI=0.06-1.91, P = 0.0331). In addition, the frequency of GSTP1 genotypes distribution achieved no significance when assessed according to severity of asthma, degree of airway obstruction, control of asthma, atopic status and IgE level.
CONCLUSIONS: The present study does not support a substantial role of GSTP1 gene polymorphism in the development of asthma. Also, it is not related to the severity of asthma, degree of airway obstruction, degree of control of asthma and/or atopy. However, large studies with accurate measurement of the environmental exposure are needed in order to reach adequate power to detect gene-environment interactions and other genes involved in the antioxidant pathway.
CLINICAL IMPLICATIONS: Advances in asthma management are likely to depend on a better understanding of how genetic factors influence susceptibility and outcome in this disease.
DISCLOSURE: The following authors have nothing to disclose: Mahmoud Mahmoud, Heba Kassem, Nashwa AbdelWahab, Abeer Saad, Pacent Moez
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