Dataset Information

Genetic predisposition for atopy and allergic rhinitis in the Singapore Chinese population.

ABSTRACT: The prevalence of allergic diseases is high globally, but especially in developed countries, with one in five to one in four individuals affected worldwide. The World Health Organization's "Allergic Rhinitis and its Impact on Asthma 2008 Update" guidelines stated explicitly that over 600 million patients from all countries, all ethnic groups and all ages suffer from allergic rhinitis (AR). There are clear evidences to support the concept that allergic diseases are influenced by genetic predisposition and environmental factors. The genetic basis of AR has been evaluated more intensively in the recent 10-20 years. Advances in technology and statistical methods, such as genome-wide association studies (GWAS) have enabled millions of single nucleotide polymorphisms (SNPs) to be genotyped at rapid pace and for less cost. However these studies have not yet answered the entire heritability profile of the disease. Additionally, environmental influences on these genetic variants cannot be discounted. Hence these allergic diseases must be evaluated as a complex interplay between genetic and environmental factors. This review focuses on the genetic basis of AR, with special emphasis on studies performed in Singapore. Candidate gene based studies and GWAS performed in Singapore cohorts have been discussed to suggest how these diseases could be understood better in a Singapore context which is still applicable to research in AR globally.

SUBMITTER: Wang de Y

PROVIDER: S-EPMC3206245 | biostudies-literature | 2011 Oct

REPOSITORIES: biostudies-literature

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Genetic predisposition for atopy and allergic rhinitis in the Singapore Chinese population.

Wang De Yun de Y

Asia Pacific allergy 20111005 3

The prevalence of allergic diseases is high globally, but especially in developed countries, with one in five to one in four individuals affected worldwide. The World Health Organization's "Allergic Rhinitis and its Impact on Asthma 2008 Update" guidelines stated explicitly that over 600 million patients from all countries, all ethnic groups and all ages suffer from allergic rhinitis (AR). There are clear evidences to support the concept that allergic diseases are influenced by genetic predispos ...[more]

PMID: 22053312

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Project description:BackgroundAllergic rhinitis (AR) is characterized by the occurrence of at least 2 symptoms of nasal itching, nasal blockage, rhinorrhea, and sneezing, when not afflicted with a cold or flu, with defined atopic sensitization demonstrated by skin prick test or specific IgE responses. Besides the detriment to standard of living and economic burden of AR, both multicentre and single-cohort studies have observed an increase in AR prevalence in Asia over time.MethodsIn total, 12 872 individuals, with mean age 22.1 years (SD = 4.8), were recruited from universities in Singapore and Malaysia. Each participant provided epidemiological data based on an investigator-administered questionnaire adapted from the validated International Study of Allergies and Asthma in Childhood (ISAAC) protocol, and atopy status was determined using a skin prick test (SPT) performed by qualified staff. AR was diagnosed according to Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines and a positive SPT result.ResultsSensitization (determined by SPT) to either Blomia tropicalis or Dermatophagoides pteronyssinus was prevalent in 66.5% of the cohort. Current rhinitis (manifesting ≥2 rhinitis symptoms, within the past 12 months) was observed in 48.9% of our population, while AR, which included atopy status, was estimated at 39.4%. Sneezing and rhinorrhea were the most common symptoms among AR cases. AR prevalence decreased with increasing age (OR: 0.979; 95% CI: 0.969-0.989), while male gender (OR: 2.053; 95% CI: 1.839-2.294), and a parental history of allergic diseases (OR: 2.750; 95% CI: 2.284-3.316) were significant risk factors for AR. Upon adjustment for age, gender, and parental history, housing type (OR: 0.632; 95% CI: 0.543-0.736) and income level (>$6000 vs <$2000; OR: 2.461; 95% CI: 2.058-2.947) remained as significant risk factors for AR, while ever having kept a pet (OR: 1.167; 95% CI: 1.025-1.328) emerged as a risk factor. Conflicting results were obtained for indicators of sedentary lifestyle: frequent physical activity (OR: 1.394; 95% CI: 1.150-1.694) and increased duration spent using the TV/computer (OR: 1.224; 95% CI: 1.006-1.489) both increased the risk of AR. Lastly, we used the Quality of Diet based on Glycaemic Index Score (QDGIS) to assess the Glycaemic Index (GI) level of overall diet. We identified lower GI level of overall diet as a protective factor against AR manifestation (OR: 0.682; 95% CI: 0.577-0.807).ConclusionWhile the previously established non-modifiable risk factors for AR were present in our study population, the identification of modifiable risk factors, such as TV/computer usage, and dietary habits, opens a new area for research, both in the areas of gene-environment interaction, and management of AR.

Project description:BACKGROUND:Variation in the 10 toll-like receptor (TLR) genes has been significantly associated with allergic rhinitis (AR) in several candidate gene studies and three large genome-wide association studies. These have all investigated common variants, but no investigations for rare variants (MAF???1%) have been made in AR. The present study aims to describe the genetic variation of the promoter and coding sequences of the 10 TLR genes in 288 AR patients. METHODS:Sanger sequencing and Ion Torrent next-generation sequencing was used to identify polymorphisms in a Swedish AR population and these were subsequently compared and evaluated using 1000Genomes and Exome Aggregation Consortium (ExAC) data. RESULTS:The overall level of genetic variation was clearly different among the 10 TLR genes. The TLR10-TLR1-TLR6 locus was the most variable, while the TLR7-TLR8 locus was consistently showing a much lower level of variation. The AR patients had a total of 37 promoter polymorphisms with 14 rare (MAF???1%) and 14 AR-specific polymorphisms. These numbers were highly similar when comparing the AR and the European part of the 1000Genomes populations, with the exception of TLR10 where a significant (P?=?0.00009) accumulation of polymorphisms were identified. The coding sequences had a total of 119 polymorphisms, 68 were rare and 43 were not present in the European part of the 1000Genomes population. Comparing the numbers of rare and AR-specific SNPs in the patients with the European part of the 1000Genomes population it was seen that the numbers were quite similar both for individual genes and for the sum of all 10 genes. However, TLR1, TLR5, TLR7 and TLR9 showed a significant excess of rare variants in the AR population when compared to the non-Finnish European part of ExAC. In particular the TLR1 S324* nonsense mutation was clearly overrepresented in the AR population. CONCLUSIONS:Most TLR genes showed a similar level of variation between AR patients and public databases, but a significant excess of rare variants in AR patients were detected in TLR1, TLR5, TLR7, TLR9 and TLR10. This further emphasizes the frequently reproduced TLR10-TLR1-TLR6 locus as being involved in the pathogenesis of allergic rhinitis.

Dataset Information

Genetic predisposition for atopy and allergic rhinitis in the Singapore Chinese population.

Publications

Genetic predisposition for atopy and allergic rhinitis in the Singapore Chinese population.

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