Polymorphisms in the IL-4, IL-4 receptor alpha chain, TNF-alpha, and lymphotoxin-alpha genes and risk of asthma in Hong Kong Chinese adults.
BACKGROUND
Susceptibility to the development of asthma and other atopic diseases is known to be associated with genetic components. However, association studies with interleukin-4 (IL-4), IL-4 receptor alpha subunit (IL-4R alpha), tumor necrosis factor-alpha (TNF-alpha) and lymphotoxin-alpha (LT-alpha) genes were inconclusive, as both positive and negative results were obtained in several populations studied. We aimed to investigate the association of the polymorphisms for IL-4 (C-589T), IL-4R alpha (Gln576Arg), TNF-alpha (G-308A) and LT-alpha (A252G) genes as candidates and asthma in adult Hong Kong Chinese population.


METHODS
The association study was conducted in an age- and smoking status-matched case-control design in asthma patients (n = 292) and healthy controls (n = 292) using polymerase chain reaction and restriction fragment length polymorphism.


RESULTS
No significant differences were found in allele and genotype frequencies of all four genes between patients and controls. After stratification by atopic status, the heterozygous AG genotype of LT-alpha (A252G) was found to increase risk of asthma in atopic population [odds ratio (OR) = 2.00, 95% CI 1.09-3.67, p = 0.024]. When stratified by smoking status, we found increased risk of asthma with subjects carrying the heterozygous AG and homozygous GG genotypes of LT-alpha in ever-smokers (OR = 2.73, 95% CI 1.11-6.69, p = 0.028 for heterozygotes; OR = 3.34, 95% CI 1.16-9.62, p = 0.026 for homozygotes).


CONCLUSIONS
Our results suggest that the variability of LT-alpha genotypes may have potential implications for individual susceptibility to asthma in atopic or in ever-smoking Chinese adults in Hong Kong.
Mak
Judith C W
JC
Division of Respiratory Medicine, Department of Medicine, The University of Hong Kong, Hong Kong, SAR, China.
Ko
Fanny W S
FW
Chu
Chung M
CM
Leung
Helen C M
HC
Chan
Henry W
HW
Cheung
Amy H K
AH
Ip
Mary S M
MS
Chan-Yeung
Moira
M
D000328:Adult; D044466:Asian People / Q000235:genetics; D001249:Asthma / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D006723:Hong Kong / Q000208:ethnology; D006801:Humans; D015847:Interleukin-4 / Q000235:genetics; D053662:Interleukin-4 Receptor alpha Subunit / Q000235:genetics; D008233:Lymphotoxin-alpha / Q000235:genetics*; D008297:Male; D011110:Polymorphism, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
D053662:Interleukin-4 Receptor alpha Subunit; D008233:Lymphotoxin-alpha; D014409:Tumor Necrosis Factor-alpha; D015847:Interleukin-4