Association between Val66Met polymorphisms in brain-derived neurotrophic factor gene and asthma risk: a meta-analysis.
OBJECTIVE
The Val66Met polymorphisms in brain-derived neurotrophic factor (BDNF) gene have been reported to be associated with asthma risk, while the results are inconclusive. Considering a single study may lack the power to provide reliable conclusion, we performed a meta-analysis to investigate the association between the Val66Met polymorphisms and asthma susceptibility.


METHODS
A comprehensive literature search of PubMed, Embase, China National Knowledge Infrastructure (CNKI) and Wanfang databases was conducted before February 12, 2015. The pooled odds ratio (OR) with 95 % confidence intervals (CIs) were calculated.


RESULTS
Six eligible studies with a total of 3501 subjects were finally included in this meta-analysis. Overall, a significantly increased risk was detected in the Val66Met G allele (G vs. A: OR 1.33, 95 % CI 1.19-1.49, P = 5.61E-07; GG vs. GA + AA: OR 1.48, 95 % CI 1.20-1.83, P = 3.14E-04; GG vs. GA: OR 1.48, 95 % CI 1.17-1.89, P = 0.001; GG vs. AA: OR 1.62, 95 % CI 1.20-2.19, P = 0.002). Moreover, stratification by ethnicity indicated marked association between the Val66Met G allele and asthma risk in Caucasians (G vs. A: OR 1.29, 95 % CI 1.12-1.49, P = 0.001; GG + GA vs. AA: OR 1.59, 95 % CI 1.03-2.46, P = 0.039; GG vs. GA + AA: OR 1.32, 95 % CI 1.11-1.57, P = 0.001; GG vs. GA: OR 1.28, 95 % CI 1.07-1.53, P = 0.007; GG vs. AA: OR 1.72, 95 % CI 1.11-2.68, P = 0.015).


CONCLUSIONS
Our present meta-analysis suggests that the Val66Met polymorphisms in BDNF gene are potentially associated with asthma risk in Caucasians. Further well-designed case-control studies with larger sample size and more ethnic groups are needed to confirm these conclusions.
Department of Respiratory Medicine, The First Affiliated Hospital of Medical College, Xi'an Jiaotong University, No.277, West Yanta Road, 710061, Xi'an, Shaanxi, People's Republic of China.
Xinming
X
Xie
Department of Respiratory Medicine, The First Affiliated Hospital of Medical College, Xi'an Jiaotong University, No.277, West Yanta Road, 710061, Xi'an, Shaanxi, People's Republic of China.
Yanting
Y
Zhu
Department of Pathology, The First Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, China.
Jiaojiao
J
Zhang
Department of Respiratory Medicine, The First Affiliated Hospital of Medical College, Xi'an Jiaotong University, No.277, West Yanta Road, 710061, Xi'an, Shaanxi, People's Republic of China.
Cui
C
Zhai
Department of Respiratory Medicine, The First Affiliated Hospital of Medical College, Xi'an Jiaotong University, No.277, West Yanta Road, 710061, Xi'an, Shaanxi, People's Republic of China.
Wei
W
Feng
Department of Respiratory Medicine, The First Affiliated Hospital of Medical College, Xi'an Jiaotong University, No.277, West Yanta Road, 710061, Xi'an, Shaanxi, People's Republic of China.
Yilin
Y
Pan
Department of Respiratory Medicine, The First Affiliated Hospital of Medical College, Xi'an Jiaotong University, No.277, West Yanta Road, 710061, Xi'an, Shaanxi, People's Republic of China.
Lu
L
Liu
Department of Respiratory Medicine, The First Affiliated Hospital of Medical College, Xi'an Jiaotong University, No.277, West Yanta Road, 710061, Xi'an, Shaanxi, People's Republic of China.
Xiaofan
X
Su
Department of Respiratory Medicine, The First Affiliated Hospital of Medical College, Xi'an Jiaotong University, No.277, West Yanta Road, 710061, Xi'an, Shaanxi, People's Republic of China.
Lan
L
Yang
Department of Respiratory Medicine, The First Affiliated Hospital of Medical College, Xi'an Jiaotong University, No.277, West Yanta Road, 710061, Xi'an, Shaanxi, People's Republic of China. manxiangli@hotmail.com.
Manxiang
M
Li
D001249:Asthma / Q000235:genetics*; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics*; D020022:Genetic Predisposition to Disease; D006801:Humans; D011110:Polymorphism, Genetic
D019208:Brain-Derived Neurotrophic Factor
Asthma; BDNF; Meta-analysis; Polymorphism