Relationship between the IL-12B promoter polymorphism and allergic rhinitis, familial asthma, serum total IgE, and eosinophil level in asthma patients.

BACKGROUND IL-12B is a strong candidate gene for asthma. OBJECTIVES We investigated the relationship between IL-12B and asthma, allergic rhinitis, familial asthma, and levels of eosinophils and total immunoglobulin (Ig) E in the serum of asthma patients. METHODS The study group consisted of 53 asthma patients and 60 control patients. Serum total IgE levels, eosinophil count, and the presence of allergic rhinitis and familial asthma were determined, and the IL-12B polymorphism was analyzed. Both patients and controls were divided into 3 groups based on their genotypes-homozygous for allele 1 (Al), homozygous for allele 2 (A2), and heterozygous patients, ie, alleles 1 and 2 (A1A2). Each genotype was compared with the other genotypes and the control genotypes. RESULTS The rates for genotypes A1, A1A2, and A2 were 17%, 40%, and 43%, respectively. Male and female total IgE levels were not different between the groups (P>.05), but they were higher than in the controls (P > .05). The frequencies of allergic rhinitis and familial asthma were not different between the groups (P > .05), although allergic rhinitis in the A1A2 genotype and familial asthma in the A2 genotype were higher than in the controls (P < .05). CONCLUSIONS Our comparison of asthma patients and controls showed that familial susceptibility to asthma may be related to the A2 genotype, whereas coexistence of asthma and allergic rhinitis may be related to the A1A2 genotype. In asthmatic patients, the effects of the IL-12B polymorphism on asthma, allergic rhinitis, familial asthma, eosinophilia and total IgE levels, are controversial. We think that there is a need to investigate this hypothesis in larger series.