ABSTRACT
BACKGROUND: Asthma is a complex disease influenced by multiple genetic and environmental factors. While Madeira has the highest prevalence of asthma in Portugal (14.6%), the effect of both genetic and environmental factors in this population has never been assessed. We categorized 98 asthma patients according to the Global Initiative for Asthma (GINA) guidelines, established their sensitization profile, and measured their forced expiratory volume in 1second (FEV1) and forced vital capacity (FVC) indexes. Selected single nucleotide polymorphisms (SNPs) were analysed as potential markers for asthma susceptibility and severity in the interleukin 4 (IL4), interleukin 13 (IL13), beta-2-adrenergic receptor (ADRB2), a disintegrin and metalloprotease 33 (ADAM33), gasdermin-like (GSDML) and the signal transducer and activator of transcription 6 (STAT6) genes comparatively to a population reference set. RESULTS: Although mites are the major source of allergic sensitization, no significant difference was found amongst asthma severity categories. IL4-590*CT/TT and IL4-RP2*253183/183183 were found to predict the risk (2-fold) and severity (3 to 4-fold) of asthma and were associated with a lower FEV1 index. ADRB2-c.16*AG is a risk factor (3.5-fold), while genotype GSDML-236*TT was protective (4-fold) for moderate-severe asthma. ADAM33-V4*C was associated to asthma and mild asthma by the transmission disequilibrium test (TDT). Finally, ADAM33-V4*CC and STAT6-21*TT were associated with higher sensitization (mean wheal size ≥10mm) to house dust (1.4-fold) and storage mite (7.8-fold). CONCLUSION: In Madeira, IL4-590C/T, IL4-RP2 253/183, GSDML-236C/T and ADAM33-V4C/G SNPs are important risk factors for asthma susceptibility and severity, with implications for asthma healthcare management.
Subject(s)
Humans , Male , Female , Child , Adolescent , Polymorphism, Genetic/genetics , Asthma/genetics , Portugal , Severity of Illness Index , Biomarkers , Case-Control Studies , Vital Capacity/genetics , Forced Expiratory Volume/genetics , Risk Factors , Interleukin-4/analysis , Interleukin-4/genetics , Receptors, Adrenergic, beta-2/analysis , Receptors, Adrenergic, beta-2/genetics , Statistics, Nonparametric , Interleukin-13/analysis , Interleukin-13/genetics , Disintegrins/analysis , Disintegrins/genetics , Polymorphism, Single Nucleotide/genetics , ADAM Proteins/analysis , ADAM Proteins/genetics , STAT6 Transcription Factor/analysis , STAT6 Transcription Factor/genetics , Genotype , Neoplasm Proteins/analysis , Neoplasm Proteins/geneticsABSTRACT
In order to investigate whether Arg110Gln polymorphism in the coding region of the IL-13 gene is associated with asthma and total plasma IgE level in Han nationality in Hubei Chinese population, the allele frequency of 4257(g/a) site and Arg110Gln genotype of IL-13 was detected by using restriction fragment length polymorphism in Han nationality in Hubei Chinese population including 43 asthmatic children, 45 asthmatic adults, 31 control children and 46 control adults. Total plasma IgE was measured by Chemiluminescence assay. The results showed that the frequency of allele A at 4257 bp of IL-13 in children and adults was 0.39 and 0.32, respectively. The GlnGln form of Arg110Gln polymorphism of IL-13 gene was associated with susceptibility of asthma and elevated total plasma IgE in children (P=0.030 and 0.0009, respectively), but not with them in adults (P=0.219 and 0.174, respectively). Our results suggest that the Arg110Gln polymorphism of IL-13 gene is associated with susceptibility of asthma and elevated total plasma IgE in Chinese children of Han nationality in Hubei, but not with them in adults.