Background
Chronic obstructive pulmonary disease (COPD) is characterized by progressive airflow limitation driven by an abnormal inflammatory response of the airways to inhaled particles and fumes
1
. The disease is predicted to become the third most common cause of death and the fifth most common cause of disability in the world by 2020
2
. This disease remains under-recognized and under-diagnosed; the pathogenesis needs to be investigated.
Cigarette smoking is one of the most important risk factors for COPD, but the severity of the disease varies considerably, irrespective of the number of pack-years of smoking. Furthermore, only a minority of smokers (20%) develop the disease clinically, suggesting that in addition to smoking, COPD is partially genetically determined
3
4
. COPD may be caused by a combination of genes and environmental influences. Genes have been associated with COPD in a family-based study, and some previous studies have demonstrated familial aggregation of COPD. The heritability of COPD is estimated to be 40–77%
5
. Some other twin studies have also indicated a genetic contribution to clinically relevant parameters of pulmonary function, such as forced expiratory volume in 1s (FEV1) and forced vital capacity (FVC)
6
7
.
Many studies of candidate genes for COPD and pulmonary function have been conducted over the past few years. Above all, genome-wide association studies (GWASs) have identified some loci associated with susceptibility to COPD
8
9
10
11
12
but with varying degrees of reproducibility. Conflicting results among these studies may be attributable to ethnic differences and sample sizes. In the past, candidate gene studies have focused on a single gene or on a few genes in combination; these genes were identified based on prior knowledge or suspected mechanisms of disease pathogenesis. Nonetheless, elucidating the genetics of respiratory disorders is severely hampered by genetic heterogeneity, the low penetrance of individual disease alleles, and the potential for gene–gene and gene–environment interactions. To date, the only proven genetic risk factor for COPD is the severe deficiency of alpha-1-antitrypsin (AAT), which is associated with a predisposition to early onset panacinar (panlobular) emphysema
13
.
Furthermore, few gene studies performed on the Chinese population have focused on COPD. However, in China, the disease is increasingly prevalent. A 2007 survey of 20,245 participants in seven regions of China reported the occurrence of COPD in adults aged ≥40 years to be 8.2%
14
. Therefore, more gene-association studies are needed to identify genetic polymorphisms associated with the development of COPD in the Chinese population.
The aim of our current case–control study was to locate genes related to susceptibility to COPD in the Chinese Han population. We aimed to identify loci associated with COPD among 97 single-nucleotide polymorphisms (SNPs) of 46 genes (Table
1).
<p>Table 1</p>
Gene location and alleles of 97 single-nucleotide polymorphisms (SNPs)
SNP_ID
Gene
Chrom-osome
Alleles
SNP_ID
Gene
Chrom-osome
Alleles
References listed in supplemental document.
rs1800610
1
TNF-α
6
C/T
rs673400
14
SERPINA2
2
C/G
rs1799964
1
TNF-α
6
C/T
rs7583463
15
SERPINA2
2
A/C
rs361525
2
TNF-α
6
A/G
rs2736100
8
TERT
5
G/T
rs1800629
3
TNF-α
6
A/G
rs10069690
8
TERT
5
C/T
rs2808630
4
CRP
1
C/T
rs34829399
8
TERT
5
C/T
rs1205
5
CRP
1
C/T
rs4246742
8
TERT
5
A/T
rs1130864
4
CRP
1
C/T
rs2736118
8
TERT
5
A/G
rs1059823
6
SLC11A1
2
A/G
rs2736122
8
TERT
5
C/T
rs1130866
7
SFTPB
2
C/T
rs2853677
8
TERT
5
C/T
rs2353397
8
HHIP
4
C/T
rs2853676
8
TERT
5
A/G
rs13147758
8
HHIP
4
A/G
rs1881457
16
IL-13
5
A/C
rs2035901
8
HHIP
4
A/G
rs1295685
16
IL-13
5
C/T
rs6537302
8
HHIP
4
A/T
rs1800925
16
IL-13
5
C/T
rs1032295
8
HHIP
4
T/G
rs2066960
16
IL-13
5
A/C
rs12504628
8
HHIP
4
C/T
rs20541
16
IL-13
5
C/T
rs17019336
8
HHIP
4
A/T
rs16909898
8
PTCH1
9
A/G
rs3749893
8
TSPYL-4
6
A/G
rs10512249
8
PTCH1
9
C/T
rs4987835
9
Bcl-2
18
A/G
rs35621
17
ABCC1
16
C/T
rs2292566
10
EPHX1
1
A/G
rs2241718
18
TGF-β1
19
C/T
rs1051740
11
EPHX1
1
C/T
rs56155294
18
TGF-β1
19
C/T
rs868966
11
EPHX1
1
A/G
rs1800469
18
TGF-β1
19
C/T
rs25882
12
CSF2
5
C/T
rs2241712
18
TGF-β1
19
A/G
rs829259
13
PDE4D
5
A/T
rs2277027
8
ADAM19
5
A/C
rs6712954
14
SERPINA2
2
A/G
rs2280090
19
ADAM33
20
A/G
rs2280091
19
ADAM33
20
A/G
rs4073
12
IL-8
4
A/T
rs1435867
8
PID1
2
C/T
rs8192288
30
SOD3
4
G/T
rs10498230
8
PID1
2
C/T
rs2571445
20
TNS1
2
C/T
rs3995090
20
HTR4
5
A/C
rs1003349
31
MMP14
14
G/T
rs6889822
8
HTR4
5
A/G
rs737693
32
MMP12
11
A/T
rs1531697
9
Bcl-2
18
A/T
rs2276109
32
MMP12
11
A/G
rs1042713
21
ARDB2
5
A/G
rs1052443
8
NT5DC1
6
A/C
rs3024791
22
SFTPB
2
A/G
rs10947233
8
PPT2
6
G/T
rs511898
23
ADAM33
20
C/T
rs1051730
33
CHRNA3
15
C/T
rs2853209
23
ADAM33
20
A/T
rs11106030
20
DCN
12
A/C
rs6555465
8
ADCY2
5
A/G
rs584367
34
sPLA2s
1
C/T
rs10075508
13
PDE4D
5
C/T
rs9904270
26
CDC6
17
C/T
rs12899618
20
THSD4
15
A/G
rs2395730
8
DAAM2
6
A/C
rs3091244
8
SFXN1
5
A/C/T
rs3817928
8
GPR126
6
A/G
rs8004738
24
SERPINA1
14
A/G
rs11155242
8
GRP126
6
A/C
rs709932
24
SERPINA1
14
A/G
rs7776375
8
GPR126
6
A/G
rs4934
25
SERPINA3
14
A/G
rs6937121
8
GPR126
6
G/T
rs13706
26
CDC6
17
A/G
rs1042714
35
ARDB2
5
C/G
rs7217852
26
CDC6
17
A/G
rs1800796
36
IL-6
7
C/G
rs2077464
26
CDC6
17
A/G
rs2236307
31
MMP14
14
C/T
rs2070600
20
AGER
6
A/G
rs2236302
31
MMP14
14
C/G
rs6957
27
CDC97
19
A/G
rs2230054
37
IL-8RB
2
C/T
rs1042522
28
P53
17
C/G
rs1422795
8
ADAM19
5
A/G
rs1695
29
GSTP1
11
A/G
rs6830970
8
FAM13A
4
A/G
rs2869967
8
FAM13A
4
C/T
Methods
Subjects
In total, 331 COPD patients were recruited: 256 from the Department of Respiratory Diseases of Shanghai Rui Jin Hospital, 60 from the Shanghai Jing-an Geriatric Hospital, and 15 from the Shanghai Gong Hui Hospital. COPD was diagnosed according to the criteria established by the NHLBI/WHO Global Initiative for COPD (GOLD)
15
. The diagnoses were based on certain patient parameters (e.g., age≥40 years and smoking history of ≥20 pack-years) and on the presence of relentless and progressive symptoms: cough, productive sputum, and breathlessness over many years; airflow limitation as indicated by FEV1/ FVC≤70%; FEV1 reversibility after the inhalation of salbutamol <12% of the pre-bronchodilator FEV1 (MS-Body Diffusion, Germany). Patients were excluded if they had a comorbid diagnosis such as asthma or lung cancer, or had radiographic abnormalities suggestive of other significant respiratory diseases and any hereditary diseases.
Control subjects (n = 213) were selected from a pool of healthy people who visited the general health checkup center of Shanghai Rui Jin Hospital during the same period. The enrollment criteria for the controls were as follows: age≥40 years, smoker, no known disease, no history of any disease. Lung function was measured at baseline following the American Thoracic Society/European Respiratory Society standard procedure to confirm no evidence of airflow obstruction. All of the COPD patients and control subjects were ethnic Han Chinese. The study protocol was approved by the medical ethics committee of Shanghai Rui Jin Hospital, Shanghai Jiaotong University School of Medicine, and all participants gave written informed consent.
DNA extraction and genotyping
We chose 97 candidate SNPs identified in previously published GWASs and by searching the dbSNP database of NCBI (references in Additional file
1: Table S1). Their minor allele frequencies (MAFs) were >0.05 in the Han Chinese population we studied.
<p>Additional file 1: Table S1</p>
Primers of 97 single-nucleotide polymorphisms (SNPs) in multiplex PCR.
Click here for file
A 4-ml peripheral blood sample was obtained from each participant for DNA analysis. Plasma was separated by centrifuge and stored at −80°C until further use. We extracted genomic DNA using a QuickGene DNA whole blood kit, (Life Sciences, FUJIFILM, Japan). Any sample with DNA concentration <10 ng/ul was excluded, and another sample was acquired.
For genotyping, we first performed multiplex PCR, a variant of PCR that enables simultaneous amplification of many targets of interest in one reaction by using more than one pair of primers
16
. Mass-ARRAY™ Assay Design 2.0 software was used to design multiplex primers for each SNP: 1st PCR primer, 2nd PCR primer, and UEP primer. The primers of 97 SNPs are shown in Additional file
1: Table S1. Genotyping was achieved using the Mass-Array™ Technology platform of Sequenom, Inc. (San Diego, CA, USA). For quality control, two independent readers interpreted the results, and a random selection of 10% of all samples was retested. No discrepancies were discovered in the replicate tests. All genotyping analyses were blinded with respect to the case/control status, and all samples were analyzed in the same lab and under the same conditions. The results were 100% concordant. Several SNP samples were finally excluded because ≥10% of the genotyping data were missing.
Data analysis
Data analyses were performed using the Statistical Package for the Social Science 20.0 (SPSS, Inc., Chicago, IL, USA). Continuous variables (age, smoking history, and pulmonary function) were calculated as means (± standard deviation). The two-sided Student’s t-test was used to determine significant differences in clinical data between the COPD cases and the control subjects. The significance level for t tests of clinical information was 0.05. The χ2 test and unconditional logistic method were applied to compare genotype and allele frequencies between the two groups, logistic analysis was adjusted for age, gender and smoking. Frequencies were compared, respectively, using a p cutoff of 0.05 (like previous studies) and the Bonferroni correction method for multiple testing. The relative risk associated was estimated as an odds ratio (OR) with a 95% confidence interval (95% CI). Each of the SNPs in the control group was analyzed for Hardy-Weinberg equilibrium (HWE) using chi-square test and exact test, SNPs were excluded from the analysis if they were out of HWE (p≤0.05). Haplotype frequencies and linkage disequilibrium (LD) analyses were evaluated using PHASE and Haploview software.
Results
Study population characteristics
The study population characteristics are described in Table
2. They did not significantly differ in sex, age, or smoking history. FEV1 predictive (FEV1%) and FEV1/FVC of the case group were significantly decreased compared with the control group (p<0.05).
<p>Table 2</p>
Demographics of COPD patients and control subjects
COPD
Controls
P value
Data were presented as the means ± SD. FEV1, forced expiratory volume in 1 sec; FVC, forced vital capacity; *p<0.05 significant difference vs control.
#p<0.05 significant difference vs control.
Number
331
213
Age
61±10
58±12
Male(%)
298(90%)
209(98%)
Female(%)
33(10%)
4(2%)
Pack-years(±SD)
41±34
38±17
FEV1/FVC
54±13.8*
85±7.6*
p<0.05
FEV1/predicted(%)
49±18.1#
88±17.0#
p<0.05
Association analysis of each genotype
Eight SNPs (rs361525, rs1042713, rs34829399, rs2853677, rs2571445, rs8192288, rs2066960, and rs2230054) that deviated from HWE in the controls were removed from the association analysis. Thirteen SNPs (rs1130866, rs56155294, rs10498230, rs2035901, rs3091244, rs511898, rs2869967, rs7583463, rs2276109, rs737693, rs9904270, rs4934, and rs6830970) were also eliminated from the analysis due to lack of genotyping data in ≥10% of the sample. Finally, 76 of the 97 SNPs were included in the association analysis. The allele frequencies (Table
3) and the genotype distributions for these SNPs were analyzed in samples from 331 COPD patients and 213 control subjects. Seven SNPs tended to be associated with COPD: rs2353397, rs1800629, rs2241712, rs1205, rs20541, rs2070600, and rs10947233. Among these seven SNPs, after Bonferroni correction, rs2353397 was most strongly associated with susceptibility to COPD. The C allele (rs2353397) of the human hedgehog interacting protein (HHIP) gene occurred more frequently in COPD patients (58%) than in the control subjects (29%) (OR = 2.16, 95% CI 1.66–2.81, p<0.0001, p(Bonferroni) <0.0001). The G allele (rs1800629) of the TNF-α gene was more frequently detected in COPD patients (95%) versus control subjects (90%) (OR=1.97, 95% CI 1.21–3.21, p=0.0060, p(Bonferroni)=0.4560). The frequency of the A allele (rs2241712) of the TGF-β1 gene was significantly higher in COPD patients (52%) than in healthy controls (45%) (OR=1.24, 95% CI 0.96–1.59, p=0.0460, p(Bonferroni)=3.7848). The C allele (rs1205) of the CRP gene occurred more frequently in COPD patients (47%) compared with control subjects (40%) (OR=1.48, 95% CI 1.14–1.91, p=0.0030, p(Bonferroni)=0.2280). More COPD patients (35%) carried the T allele (rs20541) of the IL-13 gene than control subjects (28%) (OR=1.36, 95% CI 1.04–1.80, p=0.0280, p(Bonferroni)=2.1280). The G allele (rs2070600) of the AGER gene was found more frequently in COPD patients (81%) than in healthy controls (73%) (OR=1.47, 95% CI 1.08–1.98, p=0.0130, p(Bonferroni)=0.9880). The G allele (rs10947233) of the PPT2 gene occurred more frequently in COPD patients (79%) than in control subjects (72%) (OR=1.51, 95% CI 1.12–2.03, p=0.0060, p(Bonferroni)=0.4560).
<p>Table 3</p>
Allele frequencies in COPD and control subjects for SNPs
SNP
Allele
Control (n,%)
Case (n,%)
χ
2
P value
OR
OR(95%CI)
P
(Bonferroni)
Adjusted P value
Adjusted OR
Adjusted OR(95%CI)
Adjusted P
(Bonferroni)
Chi-square test and logistic analysis were used.
Logistic analysis was adjusted by potential confounders including age, gender, smoking history.
The p value with bold letters indicate those allele frequencies with significant differences between COPD and controls.
rs1059823
G
139(33)
222(34)
0.0181
0.8929
1.01
0.79-1.32
67.8604
0.8290
0.97
0.74-1.27
63.0040
A
283(67)
440(66)
rs1205
C
168(40)
308(47)
5.2168
0.0223
1.34
1.04-1.71
1.6948
0.0030
1.48
1.14-1.91
0.2280
T
252(60)
346(53)
rs17019336
A
136(32)
242(37)
2.1770
0.1401
1.21
0.94-1.57
10.6476
0.0670
1.28
0.98-1.68
5.0920
T
284(68)
416(63)
rs1799964
T
333(79)
519(79)
0.0008
0.9772
1.00
0.74-1.36
74.2672
0.8140
0.96
0.71-1.31
61.8640
C
87(21)
135(21)
rs1800610
T
71(17)
112(17)
0.0117
0.9137
1.02
0.74-1.41
69.4412
0.9007
0.98
0.70-1.38
68.4532
C
355(83)
550(83)
rs2077464
T
271(65)
420(66)
0.1909
0.6621
1.06
0.82-1.37
50.3196
0.8230
1.03
0.79-1.35
62.5480
C
149(35)
218(34)
rs2236302
C
369(88)
584(89)
0.2011
0.6539
1.09
0.75-1.59
49.6964
0.4140
1.18
0.80-1.75
31.4640
G
51(12)
74(11)
rs2292566
A
125(30)
209(32)
0.4800
0.4884
1.10
0.84-1.43
37.1184
0.7630
1.04
0.79-1.38
57.9880
G
295(70)
449(68)
rs2353397
C
123(29)
382(58)
83.3798
6.8×10
-20
3.29
2.54-4.28
5.2×10
-18
<0.0001
2.16
1.66-2.81
<0.0001
T
297(71)
280(42)
rs25882
T
147(35)
240(36)
0.2421
0.6227
1.07
0.83-1.38
47.3252
0.4650
1.10
0.85-1.44
35.3400
C
273(65)
418(64)
rs2808630
C
66(16)
119(18)
1.0136
0.3140
1.18
0.85-1.65
23.8640
0.2120
0.86
0.69-1.09
16.1120
T
354(84)
539(82)
rs3749893
A
286(67)
454(69)
0.6232
0.4299
1.11
0.86-1.44
32.6724
0.4510
1.11
0.84-1.46
34.2760
G
140(33)
200(31)
rs4987835
A
236(56)
382(60)
1.7185
0.1899
1.19
0.92-1.51
14.4324
0.2950
1.15
0.88-1.49
22.4200
G
184(44)
252(40)
rs709932
A
73(17)
131(20)
1.2714
0.2595
1.20
0.87-1.65
19.7220
0.2860
1.19
0.86-1.65
21.7360
G
347(83)
519(80)
rs7217852
A
273(65)
434(66)
0.0652
0.7985
1.03
0.80-1.34
60.6860
0.8460
1.03
0.79-1.34
64.2960
G
147(35)
226(34)
rs7776375
A
270(63)
438(66)
0.8832
0.3473
1.13
0.88-1.46
26.3948
0.2570
1.17
0.89-1.52
19.5320
G
156(37)
224(34)
rs10069690
C
331(80)
520(81)
0.0264
0.8709
1.03
0.75-1.40
66.1884
0.6480
1.08
0.78-1.48
49.2480
T
81(20)
124(19)
rs1051740
T
247(60)
403(61)
0.0424
0.8369
1.03
0.79-1.32
63.6044
0.8910
1.02
0.79-1.32
67.7160
C
163(40)
259(39)
rs11155242
A
372(90)
604(91)
0.5784
0.4469
1.18
0.77-1.79
33.9644
0.2560
1.28
0.83-1.94
19.4560
C
42(10)
58(9)
rs1295685
T
118(29)
221(33)
2.8124
0.0935
1.26
0.96-1.64
7.1060
0.1730
1.21
0.92-1.60
13.1480
C
296(71)
441(67)
rs1435867
C
55(13)
90(14)
0.0200
0.8877
1.03
0.72-1.47
67.4652
0.5300
0.89
0.62-1.29
40.5080
T
355(87)
566(86)
rs16909898
G
33(8)
54(8)
0.0101
0.9200
1.02
0.65-1.61
69.9200
0.3140
0.79
0.50-1.25
23.8640
A
379(92)
606(92)
rs1881457
A
308(74)
495(75)
0.0726
0.7876
1.04
0.78-1.38
59.8576
0.9120
1.02
0.76-1.36
69.3120
C
108(26)
167(25)
rs2241718
T
114(28)
206(31)
1.4433
0.2296
1.18
0.90-1.55
17.4496
0.2930
1.16
0.88-1.53
22.2680
C
298(72)
456(69)
rs2277027
C
64(15)
106(16)
0.0586
0.8088
1.04
0.74-1.46
61.4688
0.8350
0.96
0.68-1.36
63.4600
A
350(85)
556(84)
rs2736100
T
231(57)
368(58)
0.1539
0.6948
1.05
0.82-1.35
52.8048
0.6340
1.06
0.82-1.38
48.1840
G
173(43)
262(42)
rs35621
C
305(74)
499(75)
0.1317
0.7167
1.05
0.79-1.40
54.4692
0.3480
1.15
0.86-1.54
26.4480
T
105(26)
163(25)
rs3995090
C
288(70)
461(71)
0.1521
0.6965
1.06
0.80-1.39
52.9340
0.4200
1.12
0.84-1.48
31.9200
A
122(30)
185(29)
rs4246742
A
244(60)
429(65)
3.0339
0.0815
1.25
0.97-1.61
6.1940
0.0510
1.32
1.01-1.71
3.8760
T
166(40)
233(35)
rs6712954
G
321(78)
545(82)
3.1679
0.0751
1.32
0.97-1.79
5.7076
0.0560
1.38
1.01-1.89
4.2560
A
91(22)
117(18)
rs829259
A
137(33)
233(35)
0.4250
0.5145
1.09
0.84-1.41
39.1020
0.9300
1.01
0.77-1.32
70.6800
T
275(67)
429(65)
rs10075508
T
69(16)
108(17)
0.0253
0.8736
1.03
0.74-1.43
66.3936
0.9070
1.02
0.72-1.44
68.9320
C
357(84)
544(83)
rs10512249
T
33(8)
52(8)
0.0606
0.8056
1.06
0.67-1.67
61.2256
0.4950
1.16
0.75-1.80
37.6200
C
383(92)
570(92)
rs12899618
G
370(89)
579(89)
0.0806
0.7765
1.06
0.72-1.56
59.0140
0.6010
1.11
0.75-1.65
45.6760
A
48(11)
71(11)
rs13706
G
272(65)
427(65)
0.0598
0.8068
1.03
0.80-1.34
61.3168
0.8300
0.97
0.75-1.27
63.0800
A
148(35)
225(35)
rs1531697
A
255(61)
411(63)
0.5370
0.4637
1.10
0.85-1.41
35.2412
0.4750
1.10
0.85-1.43
36.1000
T
163(39)
239(37)
rs1800925
T
62(15)
105(17)
0.8620
0.3531
1.18
0.84-1.66
26.8356
0.1000
1.32
0.94-1.85
7.6000
C
352(85)
507(83)
rs3024791
G
388(93)
616(95)
1.5299
0.2161
1.39
0.82-2.34
16.4236
0.3820
1.25
0.76-2.06
29.0320
A
28(7)
32(5)
rs6537302
A
310(75)
480(77)
0.7206
0.3959
1.13
0.85-1.51
30.0884
0.9110
1.10
0.76-1.36
69.2360
T
104(25)
142(23)
rs6555465
G
195(46)
310(48)
0.4399
0.5072
1.09
0.85-1.39
38.5472
0.5010
1.09
0.85-1.41
38.0760
A
231(54)
338(52)
rs673400
C
178(43)
278(43)
0.0062
0.9371
1.01
0.79-1.30
71.2196
0.9280
0.99
0.76-1.28
70.5280
G
238(57)
368(57)
rs6889822
G
268(64)
417(65)
0.0594
0.8073
1.03
0.80-1.34
61.3548
0.5000
1.10
0.84-1.43
38.0000
A
148(36)
223(35)
rs8004738
G
184(44)
275(44)
0.0092
0.9236
1.01
0.79-1.30
70.1936
0.6650
1.01
0.82-1.37
50.5400
A
232(56)
351(56)
rs1003349
G
238(57)
392(60)
0.8897
0.3456
1.13
0.88-1.45
26.2656
0.2340
1.17
0.90-1.51
17.7840
T
178(43)
260(40)
rs1032295
T
320(75)
523(80)
3.1870
0.0742
1.30
0.97-1.74
5.6392
0.1130
1.28
0.94-1.73
8.5880
G
106(25)
133(20)
rs1042522
C
184(44)
304(47)
0.8170
0.3660
1.12
0.88-1.43
27.8160
0.4090
1.11
0.86-1.44
31.0840
G
236(56)
348(53)
rs1052443
C
281(67)
457(71)
1.7602
0.1846
1.20
0.92-1.56
14.0296
0.1610
1.22
0.93-1.60
12.2360
A
139(33)
189(29)
rs12504628
T
305(72)
475(72)
0.0847
0.7710
1.04
0.79-1.37
58.5960
0.9810
1.04
0.76-1.33
74.5560
C
121(28)
181(28)
rs1695
G
72(17)
126(19)
0.6673
0.4140
1.14
0.83-1.57
31.4640
0.4650
1.13
0.82-1.57
35.3400
A
346(83)
530(81)
rs1800469
C
182(44)
315(48)
2.1252
0.1449
1.20
0.94-1.54
11.0124
0.2010
1.74
1.35-2.27
15.2760
T
234(56)
337(52)
rs20541
T
118(28)
228(35)
5.3633
0.0206
1.37
1.05-1.79
1.5656
0.0280
1.36
1.04-1.80
2.1280
C
302(72)
426(65)
rs2070600
G
312(73)
529(81)
8.1712
0.0043
1.52
1.14-2.03
0.3268
0.0130
1.47
1.08-1.98
0.9880
A
114(27)
127(19)
rs2853209
A
191(45)
305(47)
0.1953
0.6586
1.06
0.83-1.35
50.0536
0.9890
0.10
0.77-1.29
75.1640
T
231(55)
349(53)
rs4073
A
185(44)
300(46)
0.5198
0.4709
1.10
0.86-1.40
35.7884
0.2530
1.16
0.90-1.50
19.2280
T
235(56)
348(54)
rs6937121
T
254(60)
423(65)
2.1263
0.1448
1.21
0.94-1.56
11.0048
0.1720
1.20
0.92-1.56
13.0720
G
166(40)
229(35)
rs6957
G
150(36)
241(37)
0.0802
0.7771
1.04
0.80-1.34
59.0596
0.6830
1.06
0.81-1.38
51.9080
A
268(64)
415(63)
rs1051730
C
403(97)
641(97)
0.2343
0.6284
1.20
0.57-2.52
47.3252
0.6480
1.17
0.60-2.29
49.2480
T
11(3)
21(3)
rs10947233
G
299(72)
526(79)
7.4524
0.0063
1.49
1.12-1.98
0.4788
0.0060
1.51
1.12-2.03
0.4560
T
115(28)
136(21)
rs11106030
C
355(85)
560(85)
0.0013
0.9716
1.01
0.71-1.42
73.8416
0.7030
1.07
0.75-1.52
53.4280
A
63(15)
100(15)
rs1130864
T
23(6)
43(7)
0.6081
0.4355
1.23
0.73-2.07
33.0980
0.3890
1.24
0.77-2.00
29.5640
C
389(94)
591(93)
rs1800629
G
379(90)
627(95)
7.8793
0.0050
1.94
1.21-3.10
0.3800
0.0060
1.97
1.21-3.21
0.4560
A
41(10)
35(5)
rs2241712
A
188(45)
342(52)
3.9820
0.0460
1.28
1.00-1.64
3.4960
0.0498
1.24
0.96-1.59
3.7848
G
226(55)
320(48)
rs2280090
G
395(94)
629(95)
0.9844
0.3211
1.30
0.77-2.20
24.4036
0.4640
1.22
0.72-2.06
35.2640
A
27(6)
33(5)
rs2395730
A
119(28)
209(32)
1.3886
0.2386
1.17
0.90-1.54
18.1336
0.0850
1.28
0.97-1.69
6.4600
C
303(72)
453(68)
rs2736118
A
397(94)
630(95)
0.6150
0.4329
1.24
0.72-2.12
32.9004
0.2850
1.36
0.78-2.37
21.6600
G
25(6)
32(5)
rs2736122
C
388(94)
632(95)
1.5783
0.2090
1.41
0.82-2.42
15.884
0.0510
1.77
1.02-3.07
3.8760
T
26(6)
30(5)
rs3817928
A
370(89)
596(90)
0.1202
0.7288
1.07
0.72-1.61
55.3888
0.4410
1.17
0.78-1.76
33.5160
G
44(11)
66(10)
rs584367
T
91(22)
152(23)
0.1399
0.7083
1.06
0.79-1.42
53.8308
0.8590
1.03
0.76-1.39
65.2840
C
323(78)
510(77)
rs1042714
C
374(90)
607(92)
1.1947
0.2744
1.27
0.83-1.96
20.8544
0.1440
1.39
0.90-2.14
10.9440
G
40(10)
374(90)
rs13147758
A
283(69)
464(71)
0.8780
0.3487
1.14
0.87-1.49
26.5012
0.3840
1.13
0.86-1.49
29.1840
G
129(31)
186(29)
rs1422795
G
61(15)
108(16)
0.5395
0.4626
1.14
0.81-1.60
35.1576
0.8690
1.03
0.73-1.46
66.0440
A
353(85)
550(84)
rs1800796
C
293(71)
473(72)
0.1539
0.6948
1.06
0.80-1.39
52.8048
0.8250
1.03
0.78-1.36
62.7000
G
121(29)
185(28)
rs2236307
C
169(41)
286(43)
0.7270
0.3938
1.11
0.87-1.43
29.9288
0.4150
1.11
0.86-1.44
31.5400
T
245(59)
372(57)
rs2280091
A
383(93)
611(93)
0.1518
0.6968
1.10
0.68-1.77
52.9568
0.5020
1.17
0.74-1.87
38.1520
G
31(7)
45(7)
rs2853676
G
335(81)
544(83)
0.4538
0.5005
1.12
0.81-1.54
38.0380
0.2770
1.20
0.86-1.67
21.0520
A
77(19)
112(17)
rs868966
A
205(50)
337(51)
0.2934
0.5880
1.07
0.84-1.37
44.6880
0.7890
1.04
0.80-1.34
59.9640
G
209(50)
321(49)
For analysis of genotypic association of these seven SNPs under certain genotype models (Table
4), rs2353397 TT protected subjects from the disease; CC, CT carriers were more susceptible to COPD (OR=1.01, 95% CI 0.79–1.32, p<0.0001). The rs1800629 GG homozygous carriers exhibited an increased susceptibility to the disease compared with AA, GA carriers (OR=1.90, 95% CI 1.12–3.21, p=0.0170). The rs1205 CC, CT genotype increased risk for COPD compared with the TT homozygous genotype (OR=1.82, 95% CI 1.21–2.73, p=0.0040). Individuals carrying the rs20541 TT, CT genotype were at a significantly higher risk for COPD than were healthy subjects carrying the CC genotype (OR=1.47, 95% CI 1.01–2.13, p=0.0450). The rs2070600 GG homozygous carriers tended to develop COPD more frequently that AA, GA carriers (OR=1.55, 95% CI 1.06–2.26, p=0.0240). rs10947233 GG, GT carriers were associated with susceptibility to COPD compared with TT carriers (OR=3.30, 95% CI 1.47–7.44, p=0.0040).GG carriers versus GT, TT carriers (OR=1.56, 95% CI 1.07–2.27, p=0.0200).
<p>Table 4</p>
Analysis of Genotypic Association of SNPs identified under Genetic Models
SNP
Genotype model
Control (n,%)
Case (n,%)
P value*
OR*
OR(95%CI) *
* Logistic regression analysis was adjusted by potential confounders including age, gender, smoking history.
rs2353397
CC+CT
104(50)
261(79)
<0.0001
1.01
0.79-1.32
TT
106(50)
70(21)
rs2070600
GG
100(47)
213(65)
0.0240
1.55
1.06-2.26
GA+AA
113(53)
115(35)
rs10947233
GG+GT
191(92)
319(96)
0.0040
3.30
1.47-7.44
TT
16(8)
12(4)
rs10947233
GG
108(52)
207(63)
0.0200
1.56
1.07-2.27
GT+TT
99(48)
124(37)
rs1800629
GG
171(81)
296(89)
0.0170
1.90
1.12-3.21
GA+AA
39(19)
35(11)
rs1205
CC+CT
134(64)
238(73)
0.0040
1.82
1.21-2.73
TT
76(36)
89(27)
rs20541
TT+CT
99(47)
189(58)
0.0450
1.47
1.01-2.13
CC
111(53)
138(42)
The complete genotype distributions of the other SNPs are listed in Table
5. Frequencies under different genotypic models of each SNP were compared between the COPD group and the control group.
<p>Table 5</p>
Genotype frequencies of each SNP in COPD and control subjects for SNPs
SNP
Allele
Control (n,%)
Case (n,%)
Adjusted P value
Adjusted OR
Adjusted OR(95%CI)
Adjusted P
(Bonferroni)
rs1059823
GG
24(11)
39(11)
0.8120
0.93
0.52-1.67
61.7120
GA+AA
187(89)
292(89)
GG+GA
115(55)
183(55)
0.8760
0.97
0.68-1.39
66.5760
AA
96(45)
148(45)
rs17019336
AA
26(12)
35(11)
0.0100
0.14
0.09-0.22
0.7600
TA+TT
184(88)
294(89)
AA+AT
110(52)
207(63)
0.0210
1.54
1.07-2.21
1.5960
TT
100(48)
122(37)
rs1799964
TT
130(62)
206(63)
0.8010
0.95
0.66-1.38
60.8760
TC+CC
80(38)
121(37)
TT+TC
203(97)
313(96)
0.9180
0.96
0.41-2.23
69.7680
CC
7(3)
14(4)
rs1800610
TT
9(4)
13(4)
0.9940
1.00
0.41-2.44
75.5440
TC+CC
204(96)
318(96)
TT+TC
62(29)
99(30)
0.7350
1.07
0.72-1.59
55.8600
CC
151(71)
232(70)
rs2077464
TT
85(40)
138(43)
0.6620
1.09
0.75-1.57
50.3120
TC+CC
125(60)
181(57)
TT+TC
186(89)
282(88)
0.8190
0.94
0.53-1.64
62.2440
CC
24(11)
37(12)
rs2236302
CC+GC
208(99)
327(99)
0.8210
1.26
0.18-8.99
62.3960
GG
2(1)
2(1)
CC
161(77)
257(78)
0.4060
1.20
0.78-1.84
30.8560
GG+GC
49(23)
72(22)
rs2292566
AA
21(10)
36(11)
0.7410
1.11
0.61-2.0
56.3160
GG+AG
189(90)
293(89)
AA+AG
106(50)
156(47)
0.8610
1.03
0.72-1.48
65.4360
GG
rs2353397
CC
19(9)
121(37)
0.4850
1.24
0.68-2.28
36.8600
CT+TT
191(91)
210(63)
CC+CT
104(50)
261(79)
0.3740
1.18
0.82-1.69
28.4240
TT
106(50)
70(21)
rs25882
TT
30(14)
46(14)
0.9400
1.02
0.61-1.71
71.4400
CT+CC
180(86)
283(86)
TT+CT
117(56)
194(59)
0.3490
1.19
0.83-1.72
26.5240
CC
93(44)
135(41)
rs2808630
CC
4(2)
10(3)
0.4820
0.90
0.66-1.22
36.6320
CT+TT
206(98)
319(97)
CC+CT
62(30)
109(33)
0.2200
0.80
0.55-1.15
16.7200
TT
148(70)
220(67)
rs3749893
AA
100(47)
161(50)
0.4510
1.11
0.85-1.46
34.2760
AG+GG
113(53)
166(50)
AA+AG
186(87)
293(90)
0.6830
1.08
0.75-1.55
51.9080
GG
27(13)
34(10)
rs4987835
AA
65(31)
121(38)
0.2280
1.27
0.86-1.86
17.3280
AG+GG
145(69)
196(62)
AA+AG
171(81)
261(80)
0.6900
1.10
0.69-1.76
52.4400
GG
39(19)
56(20)
rs709932
AA
8(4)
16(5)
0.7950
1.13
0.45-2.84
60.4200
AG+GG
202(96)
309(95)
AG+AA
65(31)
115(35)
0.2570
1.25
0.85-1.82
19.5320
GG
145(69)
210(65)
rs7217852
AA
86(41)
141(43)
0.6180
1.01
0.76-1.58
46.9680
AG+GG
124(59)
189(57)
AA+AG
187(89)
293(89)
0.7000
0.89
0.51-1.57
53.2000
GG
23(11)
37(11)
rs7776375
AA
83(39)
148(45)
0.0900
1.37
0.95-1.98
6.8400
AG+GG
130(61)
183(55)
AA+AG
187(39)
290(45)
0.7940
0.93
0.54-1.6
60.3440
GG
26(12)
41(12)
rs10069690
TT
12(6)
7(2)
0.7100
0.93
0.64-1.35
53.9600
CT+CC
194(94)
315(98)
TT+CT
69(33)
117(36)
0.0240
3.14
1.17-9.92
1.8240
CC
137(67)
205(64)
rs1051740
TT
72(35)
123(37)
0.5730
1.12
0.76-1.63
43.5480
TC+CC
133(65)
208(63)
TT+TC
175(85)
280(85)
0.6070
0.88
0.53-1.45
46.1320
CC
30(15)
51(15)
rs11155242
AA
169(82)
276(83)
0.3060
1.27
0.80-2.01
23.2560
AC+CC
38(18)
55(17)
AA+AC
203(98)
328(99)
0.5030
1.68
0.37-7.56
38.2280
CC
4(2)
3(1)
rs1295685
TT
19(9)
37(12)
0.4470
1.27
0.69-2.32
33.9720
TC+CC
188(91)
294(88)
TT+CT
99(48)
184(56)
0.1880
1.27
0.89-1.83
14.2880
CC
108(52)
147(44)
rs1435867
CC
5(2)
7(2)
0.7660
0.83
0.24-2.85
58.2160
CT+TT
200(98)
321(98)
CC+CT
50(24)
83(25)
0.5380
0.88
0.58-1.33
40.8880
TT
155(76)
245(75)
rs16909898
GG
2(1)
1(0.3)
0.4560
0.40
0.03-4.45
34.6560
GA+AA
204(99)
329(99.7)
GG+GA
31(15)
53(16)
0.3580
0.80
0.49-1.30
27.2080
AA
175(85)
277(84)
rs1881457
AA
117(56)
187(56)
0.9540
0.99
0.69-1.42
72.5040
AC+CC
91(44)
144(44)
AA+AC
191(92)
308(93)
0.7340
1.13
0.57-2.22
55.7840
CC
17(8)
23(7)
rs2241718
TT
10(5)
26(8)
0.1380
1.80
0.83-3.88
10.4880
TC+CC
196(95)
305(92)
TT+TC
104(50)
180(54)
0.5480
1.12
0.78-1.60
41.6480
CC
102(50)
151(46)
rs2277027
CC
5(2)
10(3)
0.4990
1.47
0.49-4.44
37.9240
CA+AA
202(98)
321(97)
CC+CA
59(29)
96(29)
0.6170
0.90
0.61-1.34
46.8920
AA
148(71)
235(71)
rs2736100
TT
72(36)
108(34)
0.7840
0.95
0.65-1.39
59.5840
TG+GG
130(64)
207(66)
TT+TG
159(79)
260(83)
0.2490
1.32
0.83-2.10
18.9240
GG
43(21)
55(17)
rs35621
CC
114(56)
185(56)
0.3820
1.18
0.82-1.69
29.0320
CT+TT
91(44)
146(44)
CC+CT
191(93)
314(95)
0.5710
1.25
0.58-2.67
43.3960
TT
14(7)
17(5)
rs3995090
CC
98(48)
163(50)
0.2110
1.26
0.88-1.80
16.0360
CA+AA
107(52)
160(50)
CC+CA
190(93)
298(92)
0.6630
0.86
0.43-1.70
50.3880
AA
15(7)
25(8)
rs4246742
AA
71(35)
136(41)
0.0550
1.44
0.99-2.10
4.1800
AT+TT
134(65)
195(59)
AA+AT
173(84)
293(89)
0.1700
1.44
0.86-2.42
12.9200
TT
32(16)
38(11)
rs6712954
GG
128(62)
218(66)
0.1940
1.28
0.88-1.86
14.7440
GA+AA
78(38)
113(34)
GG+GA
193(94)
327(99)
0.0130
4.25
1.37-13.24
0.9880
AA
13(6)
4(1)
rs829259
AA
24(12)
35(11)
0.4770
0.81
0.45-1.46
36.2520
AT+TT
182(88)
296(89)
AA+AT
113(55)
198(60)
0.5920
1.11
0.77-1.59
44.9920
TT
93(45)
133(40)
rs10075508
TT
4(2)
6(2)
0.3660
0.49
0.10-2.30
27.8160
TC+CC
209(98)
320(98)
TT+TC
65(31)
102(31)
0.7280
1.07
0.73-1.58
55.3280
CC
148(69)
224(69)
rs10512249
TT
2(1)
1(0.3)
0.4560
0.40
0.04-4.45
34.6560
TC+CC
206(99)
310(99.7)
TT+TC
31(15)
51(16)
0.4150
1.27
0.71-2.27
31.5400
CC
177(85)
260(84)
rs12899618
GG
162(78)
259(79)
0.3010
1.26
0.82-1.94
22.8760
GA+AA
47(32)
66(21)
GG+GA
208(99)
320(98)
0.1430
0.20
0.02-1.71
10.8680
AA
1(1)
5(2)
rs13706
GG
85(40)
138(42)
0.7230
1.07
0.74-1.54
54.9480
GA+AA
125(60)
188(58)
GG+GA
187(89)
289(89)
0.3210
0.76
0.43-1.31
24.3960
AA
23(11)
37(11)
rs1531697
AA
75(36)
134(41)
0.2920
1.22
0.84-1.77
22.1920
AT+TT
134(64)
191(59)
AA+AT
180(86)
277(85)
0.9290
0.98
0.58-1.645
70.6040
TT
29(14)
48(15)
rs1800925
TT
6(3)
12(4)
0.7160
1.22
0.43-3.47
54.4160
TC+CC
201(97)
294(96)
TT+TC
56(27)
93(31)
0.0790
1.41
0.96-2.08
6.0040
CC
151(73)
213(69)
rs3024791
GG
181(87)
293(90)
0.3770
1.27
0.75-2.14
28.6520
GA+AA
27(13)
31(10)
GG+GA
207(99.5)
323(99.7)
0.8760
1.25
0.08-20.07
66.5760
AA
1(0.5)
1(0.3)
rs6537302
AA
115(55)
194(62)
0.5150
1.13
0.79-1.62
39.1400
AT+TT
92(45)
117(38)
AA+AT
195(94)
286(92)
0.3070
0.68
0.33-1.41
23.3320
TT
12(6)
25(8)
rs6555465
GG
40(19)
83(26)
0.1920
1.34
0.86-2.10
14.5920
GA+AA
173(81)
241(74)
GG+GA
155(73)
227(70)
0.8710
0.97
0.65-1.45
66.1960
AA
58(27)
97(30)
rs673400
CC
0(0)
0(0)
NA
NA
NA
NA
CG+GG
208(100)
323(100)
CC+CG
178(86)
278(86)
0.8190
0.94
0.56-1.57
62.2440
GG
30(14)
45(14)
rs6889822
GG
84(40)
133(42)
0.4800
1.14
0.79-1.65
36.4800
GA+AA
124(60)
187(58)
GG+GA
184(88)
284(89)
0.7550
1.10
0.62-1.95
57.3800
AA
24(12)
36(11)
rs8004738
GG
45(22)
68(22)
0.7910
1.06
0.69-1.64
60.1160
GA+AA
163(78)
245(78)
GG+GA
139(67)
207(66)
0.6880
1.08
0.74-1.60
52.2880
AA
69(33)
106(34)
rs1003349
GG
68(33)
122(37)
0.1880
1.29
0.88-1.89
14.2880
GT+TT
140(67)
204(63)
GG+GT
170(82)
270(83)
0.6130
1.13
0.70-1.83
46.5880
TT
38(18)
56(17)
rs1032295
TT
119(56)
206(63)
0.1570
1.30
0.90-1.88
11.9320
TG+GG
94(44)
122(37)
TT+TG
201(94)
317(97)
0.2380
1.70
0.70-4.12
18.0880
GG
12(6)
11(3)
rs1042522
CC
37(18)
60(18)
0.8050
1.06
0.66-1.70
61.1800
GC+GG
173(82)
266(82)
CC+CG
147(70)
244(75)
0.2860
1.25
0.83-1.86
21.7360
GG
63(30)
82(25)
rs1052443
CC
96(46)
163(50)
0.2950
1.21
0.85-1.74
22.4200
CA+AA
114(54)
160(50)
CC+CA
185(88)
294(91)
0.1970
1.49
0.81-2.71
14.9720
AA
25(12)
29(9)
rs12504628
TT
107(50)
166(50)
0.9000
0.98
0.68-1.40
68.4000
TC+CC
106(50)
162(50)
TT+TC
198(93)
309(94)
0.7810
1.11
0.54-2.27
59.3560
CC
15(7)
19(6)
rs1695
GG
5(2)
10(3)
0.4990
1.47
0.48-4.44
37.9240
GA+AA
204(98)
318(97)
GG+GA
67(32)
116(35)
0.5520
1.12
0.77-1.64
41.9520
AA
142(68)
212(65)
rs1800469
CC
39(19)
74(23)
0.9960
1.34
0.98-1.95
75.6960
TC+TT
169(81)
252(77)
CC+TC
143(69)
241(74)
0.2530
1.26
0.85-1.88
19.2280
TT
65(31)
85(26)
rs2853209
AA
42(20)
68(21)
0.4560
1.18
0.76-1.84
34.6560
AT+TT
169(80)
251(79)
AA+AT
149(71)
232(72)
0.4850
0.87
0.59-1.28
36.8600
TT
62(29)
92(28)
rs4073
AA
36(17)
68(21)
0.2460
1.32
0.83-2.09
18.6960
AT+TT
174(83)
256(79)
AA+AT
149(71)
232(72)
0.3260
1.22
0.82-1.83
24.7760
TT
61(29)
92(28)
rs6937121
TT
72(34)
141(43)
0.0280
1.52
1.05-2.20
2.1280
TG+GG
138(66)
185(57)
TT+TG
182(87)
282(86)
0.6680
0.89
0.53-1.50
50.7680
GG
28(13)
44(14)
rs6957
GG
21(10)
40(12)
0.2810
1.37
0.77-2.43
21.3560
GA+AA
188(90)
288(88)
GG+GA
129(62)
201(61)
0.8730
0.97
0.67-1.41
66.3480
AA
80(38)
127(39)
rs1051730
CC
196(95)
311(94)
0.5330
1.25
0.62-2.50
40.5080
CT+TT
11(5)
20(6)
CC+CT
207(100)
330(99.7)
NA
NA
NA
NA
TT
0(0)
1(0.3)
rs11106030
CC
153(73)
237(72)
0.9350
1.02
0.68-1.52
71.0600
CA+AA
56(27)
93(28)
CC+CA
202(96)
323(98)
0.3350
1.77
0.55-5.66
25.4600
AA
7(4)
7(2)
rs1130864
TT
0(0)
0(0)
NA
NA
NA
NA
TC+CC
206(100)
317(100)
TT+TC
23(11)
43(14)
0.3720
1.26
0.76-2.07
28.2720
CC
183(89)
274(86)
rs2241712
AA
44(21)
92(28)
0.1560
1.37
0.89-2.10
11.8560
AG+GG
163(79)
239(72)
AA+AG
144(69)
250(76)
0.2290
1.28
0.86-1.92
17.4040
GG
63(31)
81(24)
rs2280090
GG
185(88)
299(90)
0.4650
1.23
0.71-2.14
35.3400
GA+AA
26(12)
32(10)
GG+GA
210(99.5)
330(99.4)
0.8760
1.25
0.08-20.07
66.5760
AA
1(0.5)
1(0.6)
rs2395730
AA
20(9)
48(15)
0.0490
1.77
1.00-3.13
3.7240
AC+CC
191(91)
283(85)
AA+AC
99(9)
161(49)
0.3610
1.18
0.82-1.70
27.4360
CC
112(53)
170(51)
rs2736118
AA
186(88)
299(90)
0.2740
1.38
0.78-2.45
20.8240
AG+GG
25(12)
32(10)
AA+AG
211(100)
331(100)
NA
NA
NA
NA
GG
0(0)
0(0)
rs2736122
CC
181(87)
301(90)
0.035
1.84
1.04-3.24
2.6600
CT+TT
26(13)
30(10)
CC+CT
181(100)
331(100)
NA
NA
NA
NA
TT
0(0)
0(0)
rs3817928
AA
166(81)
268(81)
0.4490
1.19
0.76-1.85
34.1240
AG+GG
41(19)
63(19)
AA+AG
204(99)
328(99)
0.7860
1.25
0.25-6.26
59.7360
GG
3(1)
3(1)
rs584367
TT
10(5)
14(4)
0.5010
0.73
0.30-1.82
38.0760
TC+CC
197(95)
317(96)
TT+TC
81(39)
138(42)
0.6410
1.10
0.76-1.57
48.7160
CC
126(61)
193(58)
rs1042714
CC
168(81)
280(85)
0.1020
1.48
0.93-2.36
7.7520
GC+GG
39(19)
49(15)
CC+GC
206(99)
327(99)
0.6990
0.62
0.06-6.90
53.1240
GG
1(1)
2(1)
rs13147758
AA
102(50)
168(52)
0.6310
1.09
0.76-1.57
47.9560
AG+GG
104(50)
157(48)
AA+AG
181(88)
296(91)
0.2920
1.38
0.76-2.49
22.1920
GG
25(12)
29(9)
rs1422795
GG
5(2)
11(3)
0.4990
1.47
0.48-4.44
37.9240
GA+AA
202(98)
313(97)
GG+GA
56(27)
97(29)
0.9400
0.99
0.66-1.46
71.4400
AA
151(73)
232(71)
rs1800796
CC
110(53)
168(51)
0.5080
0.89
0.62-1.27
38.6080
CG+GG
97(47)
161(49)
CC+CG
183(88)
305(97)
0.1060
1.68
0.90-3.16
8.0560
GG
24(12)
24(3)
rs2236307
CC
41(20)
62(19)
0.9460
0.98
0.62-1.55
71.8960
CT+TT
166(80)
267(81)
CC+CT
128(62)
224(68)
0.2150
1.27
0.87-1.86
16.3400
TT
79(38)
105(32)
rs2280091
AA
178(86)
283(86)
0.6730
1.11
0.68-1.82
51.1480
AG+GG
29(14)
45(14)
AA+AG
205(99)
328(100)
NA
NA
NA
NA
GG
2(1)
0(0)
rs2853676
GG
137(67)
225(69)
0.3510
1.20
0.82-1.75
26.6760
GA+AA
69(33)
103(31)
GG+GA
198(97)
319(98)
0.3930
1.58
0.56-4.46
29.8680
AA
8(3)
9(2)
rs868966
AA
56(27)
84(26)
0.6620
0.91
0.60-1.38
50.3120
AG+GG
151(73)
245(74)
AA+AG
149(72)
253(77)
0.3970
1.20
0.79-1.80
30.1720
GG
58(28)
76(23)
Haplotype analysis
Using Haploview software, CRP gene polymorphisms were determined to be in linkage disequilibrium (D’=1.0). Using PHASE software, haplotype frequencies for the polymorphisms rs1205 and rs2808630 of CRP at chromosome 1 were compared with respect to frequency between COPD patients and healthy controls. These two SNPs formed three haplotypes: CC, CT, and TT (Table
6 and Figure
1). Among them, only the TT haplotype was more frequently detected in controls (61%) compared with COPD patients (52%) (OR=0.69, 95% CI 0.49–0.98, p=0.0377). TGF-β1 rs2241718 and CDC97 rs6957 were in linkage disequilibrium (D’=0.98); they formed two haplotypes, GC and GT. These two haplotypes were respectively more frequent in healthy controls compared with COPD patients (OR=0.33, 95% CI 0.23–0.48, p=1.88×10-9) (Table
6 and Figure
2). TGF-β1 rs1800469 and rs2241712 were also in linkage disequilibrium (D’=0.98); they formed TG and CA haplotypes. However, no significant differences between the two groups were detected (Table
6 and Figure
2).
<p>Table 6</p>
Haplotypes of the
CRP
and
TGF-β1
gene
SNPs(gene)
Haplotype
Control (n,%)
Case (n,%)
χ
2
P value
OR
OR(95%CI)
The p value with bold letters indicate those allele frequencies with significant differences between COPD and controls.
rs2241718(TGF-β1)
GC
107(50)
83(25)
36.0947
1.88×10
-9
0.33
0.23-0.48
rs6957(CDC97)
Non-GC
106(50)
248(75)
GT
107(50)
83(25)
36.0947
1.88×10
-9
0.33
0.23-0.48
Non-GT
106(50)
248(75)
rs1800469(TGF-β1)
TG
111(52)
159(48)
0.8615
0.3533
0.85
0.60-1.20
rs2241712(TGF-β1)
Non-TG
102(48)
172(52)
CA
94(44)
162(49)
1.2041
0.2725
1.21
0.86-1.71
Non-CA
119(56)
169(51)
rs1205(CRP)
TT
130(61)
172(52)
4.3163
0.0377
0.69
0.49-0.98
rs2808630(CRP)
Non-TT
83(39)
159(48)
CC
32(15)
60(18)
0.8883
0.3459
1.25
0.78-2.0
Non-CC
181(85)
271(82)
CT
51(24)
96(29)
1.6822
0.1946
1.30
0.87-1.92
Non-CT
162(76)
235(71)
<p>Figure 1</p>Linkage disequilibrium of SNPs in the CRP gene using Haploview software
Linkage disequilibrium of SNPs in the CRP gene using Haploview software. The red color indicates the higher linkage disequilibrium (D’=1.0) between rs2808630 and rs1205.
![]()
<p>Figure 2</p>Linkage disequilibrium of SNPs in the TGF-β1 and CDC97 genes using Haploview software
Linkage disequilibrium of SNPs in the TGF-β1 and CDC97 genes using Haploview software. The red color indicates the higher linkage disequilibrium (D’=0.98) between the rs2241718 and rs6957; between the rs1800469 and rs2241712.
![]()
Discussion
In this study, we sought to determine which of 76 SNPs we chose were associated with the development of COPD. Our case–control study verified that the following SNPs were associated with COPD: rs2353397 C, rs1800629 G, rs2241712 A, rs1205 C, rs20541 T, rs2070600 G, and rs10947233 G. The rs2353397 C allele was most strongly associated with COPD.
rs2353397 CC, CT genotypes of the HHIP gene were associated with susceptibility to COPD in the Chinese Han population. The HHIP gene is located at chromosome 4q31.21–31.3, position 145517578; it encodes the HHIP protein
17
. This protein is a critical regulator of the hedgehog (Hh) signalling pathway, which has been implicated in cell development, cell repair, and cancer development in multiple tissues
18
. The idea that COPD could be associated with inappropriate growth or structural defects in small airways makes HHIP an attractive candidate developmental gene. Several GWASs have also demonstrated that the 4q31 locus, which contains the HHIP gene, is associated with COPD and lung function
9
10
11
12
. A GWA meta-analysis for pulmonary function in 20,890 participants of European white ancestry revealed eight genes associated with COPD and concluded that HHIP is associated with FEV1/FVC
10
. Few studies prior to our current study have reported the SNPs of the HHIP gene related to COPD in an Asian population. Polymorphisms may lead to changes in gene expression, resulting in functional alteration and, subsequently, to COPD. According to Zhou et al. (2012)
19
, significant decreases in expression of the HHIP gene at the mRNA and protein levels were observed in COPD lungs compared with lungs of smokers with normal lung function. The risk-associated haplotype confers decreased activity on the HHIP promoter, indicating that lower HHIP expression may exacerbate smoking-induced COPD pathogenesis. Lemjabbar-Alaoui et al. (2006)
20
demonstrated that hedgehog signaling proteins are critical mediators of cigarette smoke-induced disease, such as lung cancer and chronic airway inflammatory disease, and the expression levels of hedgehog signaling proteins are modulated by HHIP. Based on our current study of HHIP polymorphisms and the Hh signaling pathway, we need to further our mechanistic research in the context of smoking.
Our results also demonstrated that rs1800629 GG carriers of the TNF-α gene were at several times the risk for COPD compared with GA, AA carriers. TNF-α is critical in the regulation of inflammation; it induces a cascade of other inflammatory cytokines, chemokines, and other growth factors; it is important in the pathogenesis of many diseases. Several gene studies have also determined that the promoter polymorphism of TNF-α is associated with chronic bronchitis or the extent of emphysematous changes. Two of these studies were performed with Caucasian subjects, two with Japanese subjects
21
22
23
24
. The promoter polymorphism may have caused varied concentrations of serum TNF-α, which have been associated with induced sputum in bronchial biopsies and with bronchoalveolar lavage fluid in stable COPD patients and during exacerbations, compared with that of control subjects
25
. Some investigators have shown that TNF-α genotypes do influence the severity of infectious diseases, while others have concluded that polymorphisms of this gene promoter are of no functional consequence
26
27
.
A polymorphism of the TGF-β1 gene, rs2241712 A, tended to be a risk-associated allele in our study. TGF-β1 is one of the important cytokines involved in the inflammatory process of COPD. TGF-β1 expression is usually increased in the airways of patients. Su et al. (2005)
28
found that more carriers of the -800A allele, or fewer carriers of the -509T allele were detected among the COPD patients, but only 84 COPD cases and 97 healthy controls participated in their research. In addition, we used a Chinese Han population, while Su et al. recruited people in a general Chinese population. Van Diemen et al. (2010)
29
showed that the TGF-β1 rs6957 SNP haplotype with the major allele of rs6957 and minor alleles of rs1800469 and rs1982073 were associated with COPD. The differences in study populations may explain these dissimilarities between our studies. Various studies have indicated that certain SNPs of the TGF-β1 gene are functional and result in higher levels of circulating TGF-β1
30
31
.
The SNP rs20541 at IL-13 gene exon 4 tended to be associated with COPD in our study. Genotype TT, CT carriers were at risk. IL-13 is a Th2 cytokine implicated in the recruitment of inflammatory cells from the blood to the lung, which may be involved in the pathogenesis of COPD. In experimental studies, the overexpression of IL-13 in the adult murine lung caused emphysema
32
. The number of IL-13+ cells was elevated in the bronchial submucosa of smokers with chronic bronchitis compared to asymptomatic smokers
33
. rs2066960, rs20541, and rs1295685 in the IL-13 gene were associated with COPD risk and lower baseline lung function in the study by Beghé et al. (2010)
34
, which used a Caucasian study population. We chose the same SNPs located in the IL-13 gene, but our results showed that only rs20541 is of significance in susceptibility to COPD in the Chinese Han population. In addition, another study revealed the role of rs20541 in another chronic airway inflammatory disease (asthma), which indicates that the polymorphism in the coding region might contribute to airflow limitation
35
.
The polymorphism of another inflammatory marker in the CRP gene, rs1205 C, was also a risk-associated allele according to our current study. Sunyer et al. (2008)
36
assessed the association between rs1205 and lung function; they demonstrated that the TT homozygous genotype in the CRP gene is associated with better lung function. Our result that the TT genotype protects people against COPD is similar to theirs because COPD is characterized by airflow limitation according to lung function. This polymorphism has been previously reported associated with varied levels of CRP in several studies
37
. Higher levels of CRP in peripheral blood may cause impaired lung function
38
.
Two other SNPs, AGER rs2070600 and PPT2 rs10947233, tended to be associated with COPD in our current study. rs2070600 GG and rs10947233 GG, GT carriers tended to develop COPD. An occidental GWAS demonstrated a role for the chromosome 6p21 locus including the AGER and PPT2 genes in COPD development in smokers
39
. Repapi et al. (2010)
12
reported a meta-analysis of GWAS results from 20,288 participants and follow-up analyses in 54,276 participants; they identified five novel, genome-wide, significant loci for pulmonary function containing AGER rs2070600, but their analysis subject group did not include Asians. In addition, rs2070600 was associated with severe COPD in a study of Caucasian smokers from Poland
40
. The two SNPs of AGER and PPT2 were also identified associated with FEV1/FVC in the 2009 work of Hancock et al.
10
.
In addition, our study revealed some haplotypes composed of rs1205 and rs 2808630 in the CRP gene, rs2241718 and rs 6957 at the TGF-β1 and CDC97 genes. In our future research, we will further analyze our data with regard to lung function.
Our research had some limitations. First, a larger sample size would have improved quality of the results. Second, although we selected 97 SNPs for the study and found some loci related to the disease, further GWASs of COPD are needed in the Chinese Han population to identify more associated polymorphisms. It is likely that more genetic risk factors than those identified in this study contribute to the development of COPD. In our future work, we will further our investigation on gene function of the genetic factors related to the development of COPD.