Association between genetic variations of the transforming growth factor ß receptor type III and asthma in a Korean population

Abstract

Transforming growth factor-beta (TGF-ß) and its receptors have been suggested to play key roles in the pathogenesis of asthma. The aim of this study was to evaluate the effects of genetic variations in the TGF-ß receptor type III (TGFBR3) on asthma and on its related phenotypes in the general population. A cohort of 2,118 subjects aged from 10 to 18 years responded to a questionnaire concerning asthma symptoms and risk factors. Methacholine airway hyperresponsiveness (AHR), skin test responses to common aeroallergens, and serum total IgE levels were evaluated in the cohort. A total of 19 SNPs for TGFBR3 were found using direct re-sequencing in 24 healthy adults. Of these, informative SNPs [+44T>C (S15F) and +2753G>A at 3'UTR] were selected and scored using the high throughput single base extension method. Atopy was identified in subjects with 44T>C allele [P=0.04, OR (95% CI)=0.79 (0.62-0.99)] and in subjects with Ht1 (CG) more frequently than in subjects with other haplotypes [P=0.04, OR (95% CI)=1.27 (1.01-1.59)]. The A allele in 2753G>A was more common in subjects with non-atopic asthma [OR (95% CI)=1.76 (1.01-3.05)]. A significant association was found between non-atopic asthma and 44T_2753A [OR (95% CI) =2.16 (1.22-3.82)]. Genetic variations in TGFBR3 appear to be associated with a genetic predisposition to development of asthma and to phenotypes of asthma. Also, the minor allele 2753G and the haplotype TA in the TGFBR3 gene were associated with a pathogenesis of non-atopic asthma.

Figure 1

Genomic organization of TGFBR III and pairwise linkage disequilibium of 19 informative SNPs in the general population. The SNPs selected for scoring are shown in bold. Individual identified SNPs and their locations are shown in the gene. Distributions of 19 screened SNPs of TGFBR3 (minor allele frequency>2%) on human chromosome 1p33-p32. Bold letters indicate locations of the informative SNPs, +44C>T [S15F (Serine → Phenylalanine at codon 15)] in exon 3 and 2753G>A (3'UTR) in exon 18 that were identified.

Figure 2

Association between the haplotypes of the skin index and total IgE (Ht1 dominant model). Haplotype analysis showed that atopy was greater in subjects with Ht1 (CG) than in subjects with the other haplotypes [P = 0.04, OR (95% CI) = 1.27 (1.01-1.59) in a dominant model]. Haplotype analysis of total serum IgE showed that Ht1 was more prevalent than other haplotypes (P = 0.008 in a dominant model).