What we know about the genetics of asthma at the beginning of the 21st century

The association forecasting of 13 variants within seven asthma susceptibility genes on 3 serum IgE groups in Taiwanese population by integrating of adaptive neuro-fuzzy inference system (ANFIS) and classification analysis methods

Asthma is one of the most common chronic diseases in children. It is caused by complicated coactions between various genetic factors and environmental allergens. The study aims to integrate the concept of implementing adaptive neuro-fuzzy inference system (ANFIS) and classification analysis methods for forecasting the association of asthma susceptibility genes on 3 serum IgE groups. The ANFIS model was trained and tested with data sets obtained from 425 asthmatic subjects and 483 non-asthma subjects from the Taiwanese population. We assessed 13 single-nucleotide polymorphisms (SNPs) in seven well-known asthma susceptibility genes; firstly, the proposed ANFIS model learned to reduce input features from the 13 SNPs. And secondly, the classification will be used to classify the serum IgE groups from the simulated SNPs results. The performance of the ANFIS model, classification accuracies and the results confirmed that the integration of ANFIS and classified analysis has potential in association discovery.

An association study of 13 SNPs from seven candidate genes with pediatric asthma and a preliminary study for genetic testing by multiple variants in Taiwanese population

INTRODUCTION

Asthma is one of the most common chronic diseases in children. It is caused by complex interactions between various genetic factors and exposures to environmental allergens and irritants. Because of the heterogeneity of the disease and the genetic and cultural differences among different populations, a proper association study and genetic testing for asthma and susceptibility genes is difficult to perform.

MATERIALS AND METHODS

We assessed 13 single-nucleotide polymorphisms (SNPs) in seven well-known asthma susceptibility genes and looked for association with pediatric asthma using 449 asthmatic subjects and 512 non-asthma subjects in Taiwanese population.

RESULTS

CD14-159 C/T and MS4A2 Glu237Gly were identified to have difference in genotype/allele frequencies between the control group and asthma patients. Moreover, the genotype synergistic analysis showed that the co-contribution of two functional SNPs was riskier or more protective from asthma attack. Our study provided a genotype synergistic method for studying gene-gene interaction on polymorphism basis and genetic testing using multiple polymorphisms.

CD14 promoter polymorphisms in atopic families: implications for modulated allergen-specific immunoglobulin E and G1 responses

BACKGROUND

CD14 promoter DNA sequence polymorphisms for the endotoxin receptor gene have been implicated in modulating allergen-specific immunoglobulin (Ig)E responses in randomly selected individuals with atopy. We sought to determine if a single nucleotide polymorphism in the CD14 promoter region is associated with atopy in atopic families, and to assess its influence on serum levels of CD14 and allergen-specific IgE and IgG1 responses.

METHODS

We screened 367 members of 91 Caucasian nuclear families with a history of asthma for pulmonary function by spirometry, including methacholine challenge to detect bronchial hyperreactivity, and atopy by serum total IgE and skin prick test to 14 allergens. The CD14 promoter single nucleotide polymorphism was analyzed in DNA isolated from peripheral blood mononuclear cells to identify C/C, C/T and T/T genotypes. Serum tests were done for soluble CD14 (sCD14) and dust mite-specific antibody (Der p 1-IgG1).

RESULTS

Serum sCD14 levels were not associated with clinical phenotypes (asthma, bronchial hyperreactivity or atopy). However, sCD14 levels were inversely related to both allergen-specific IgE and Der p 1-IgG1 production, but only among those with evidence of atopic sensitization. Linear regression analysis, accounting for random family effects, demonstrated a higher production of allergen-specific IgE or Der p 1-IgG1 associated with the T/T genotype and a lower level of specific IgE and IgG1 production associated with sCD14 levels.

CONCLUSIONS

An element of the innate immune system (CD14) has profound effects upon modulating the acquired allergen-specific immunoglobulin responses among those with an inherited atopic predisposition.

Genetics of asthma

As is becoming increasingly apparent, both atopy and asthma (however they are clinically defined) are a diverse group of related conditions, which are similarly disparate in their origins. Despite this, genetic factors are clearly operational. Speaking to their relatedness, linkages have been found between similar chromosomal sites for both atopy and asthma. Speaking to their divergence, there are also reports of the same phenotypes displaying linkage to different chromosomal areas. The likely explanation for this is that both the atopy and asthma phenotypes are polygenetic, requiring that multiple genes (some of them common to both) be expressed. For example, it may be that three genes, such as "a," "b," and "c," are involved in the development of skin test reactivity. Having only two of these genes, such as "a" and "b" or "b" and "c," alone does not result in the development of the defined phenotype of skin test reactivity. At the same time, it may be that to develop asthma one also needs three genes, such as "c", "d," and "e." One gene "c" involved in atopy inflammation is needed for both asthma and skin test reactivity. Genes "a" and "b" are also needed to be present for skin test reactivity, and a different set of genes, "d" and "e," are needed for asthma to develop. These genes "a" and "b" may be needed to localize the process in the skin and "d" and "e" to localize the process in the lung (Fig. 1). In addition to having the genetic predisposition for atopy and its associated conditions, environmental interactions are involved. Environmental conditions may be the initiating trigger and cause a shift in the balance between the protection and susceptibility of getting the clinical picture. In summary, atopy and asthma seem to be related conditions, involving both environmental and genetic factors, most likely consisting of multiple genes, which may interact with each other and the environment. A deeper [figure: see text] understanding of these genetic bases and the roles that environmental factors play in the development and manifestations of these conditions will provide better methods of diagnosis and treatment.