Correlations between VEGF +936C/T and -634C/G gene polymorphisms and PE have been widely studied[17-25], but the conclusions of studies in different regions are inconsistent. Some studies had a small sample size (N≤100)[28, 40-42], which may have affected the accuracy of the results. To clarify the distributions of the +936C/T and -634C/G allele frequencies in different parts of the world, the distributions of +936C/T and -634C/G alleles in published literature control samples were analysed (the number of control samples in the group>100). Analysis of the +936C/T locus included data from 8 studies. Chi-square analysis showed that the distribution of T alleles had significant regional differences among China, Korea, Philippines, Iran, Sri-Lanka and Tunisia (χ2=30.965, P<0.001); -634G/C locus analysis included data from 4 studies. The chi-square analysis showed that the distribution of C alleles had significant regional differences among Korea, Iran, Tunisia and Brazil (χ2=63.508, P<0.001). The results are shown in Table 1.
Table 1 The distributions of the VEGF +936C/T and -634G/C allele frequencies in different regions of the world
Region
|
Published time
|
VEGF-1
|
Sample size (controls only)
|
Allele (N)
|
T Allele frequency(%)
|
χ2
|
P
|
C
|
T
|
China(Hunan)[17]
|
2009
|
rs3025039 (+936C/T)
|
231
|
377
|
85
|
18.40%
|
30.965
|
<0.001
|
China(Shenzhen)[18]
|
2019
|
286
|
477
|
95
|
16.61%
|
KoreanⅠ[19]
|
2007
|
237
|
374
|
90
|
19.40%
|
KoreanⅡ[20]
|
2007
|
209
|
355
|
63
|
15.07%
|
Philippines(Manila)[21]
|
2016
|
190
|
324
|
56
|
14.74%
|
Iran(Tehran)[22]
|
2018
|
191
|
332
|
50
|
13.09%
|
Sri-Lanka(Colombo)[23]
|
2012
|
168
|
306
|
30
|
8.93%
|
Tunisian(Sousse)[24]
|
2017
|
300
|
534
|
66
|
11.00%
|
Region
|
Published time
|
VEGF-2
|
Sample size (controls only)
|
Allele (N)
|
C Allele frequency(%)
|
χ2
|
P
|
G
|
C
|
KoreanⅠ[19]
|
2007
|
rs2010963 (-634G/C)
|
237
|
255
|
183
|
41.78%
|
63.508
|
<0.001
|
Iran(Zahedan)[16]
|
2015
|
201
|
262
|
140
|
34.83%
|
Tunisian(Sousse)[24]
|
2017
|
300
|
246
|
354
|
59.00%
|
Brazil(Uberaba)[25]
|
2014
|
210
|
226
|
194
|
46.19%
|
To verify whether the subjects included in this study came from the same group, the +936C/T and -634G/C genotype distributions were subjected to HWE testing. The results showed that the distributions of genotypes in the Han, Uyghur, Hui, and Kazakh populations and the total sample were all in HWE (P >0.05), indicating that the research sample conformed to the genetic balance of the population, and the data were representative of the population. As shown in Table 2, the chi-square test results showed that the frequencies of the +936C/T and -634G/C alleles in healthy women in Xinjiang were significantly different among the Han, Uyghur, Hui and Kazak populations (χ2 = 8.837, P = 0.032; χ2 = 11.585, P = 0.009). Pairwise comparisons between ethnic groups showed that the allele frequencies of the two loci were significantly different between the Han and Uygur populations (P = 0.011 and P = 0.001) (results are not shown).
Table 2 The allele frequencies of VEGF +936C/T and-634G/C and their comparison among the different populations
Populations
|
VEGF-1
|
Genotype distributions(N,%)
|
T Allele frequency(%)
|
HWE-P
|
χ2,P
|
VEGF-2
|
Genotype distributions(N,%)
|
G Allele frequency(%)
|
HWE-P
|
χ2,P
|
CC
|
CT
|
TT
|
GG
|
GC
|
CC
|
Han*
|
977
|
rs3025039
(+936C/T)
|
654(67%)
|
292(30%)
|
31(3%)
|
18.12%
|
0.28
|
8.837,
0.032
|
rs2010963 (-634G/C)
|
348(36%)
|
469(48%)
|
160(16%)
|
40.38%
|
0.93
|
11.585,
0.009
|
Uighur*
|
323
|
239(74%)
|
79(24%)
|
5(2%)
|
13.78%
|
0.6
|
146(45%)
|
140(43%)
|
37(11%)
|
33.13%
|
0.7
|
Hui
|
144
|
103(72%)
|
38(26%)
|
3(2%)
|
15.28%
|
0.82
|
53(37%)
|
75(52%)
|
16(11%)
|
37.15%
|
0.17
|
Kazakh
|
64
|
48(75%)
|
16(25%)
|
0(0%)
|
12.5%
|
0.25
|
26(40.63%)
|
31(48.44%)
|
7(10.94%)
|
35.16%
|
0.62
|
Other
|
35
|
26(74.29%)
|
7(20%)
|
2(5.71%)
|
15.71%
|
0.15
|
|
13(37.14%)
|
16(45.71%)
|
6(17.14%)
|
40%
|
0.78
|
|
All samples
|
1551
|
1077(69%)
|
433(28%)
|
41(3%)
|
16.6%
|
0.75
|
|
591(38%)
|
732(47%)
|
228(15%)
|
38.3%
|
0.96
|
|
*The allele frequencies of the two loci are significantly different between the Han and Uygur populations
The comparisons of the general clinical data of the case and control groups are shown in Table 3. Pregnant women in the PE group had higher body mass index (BMI) values before pregnancy, higher systolic and diastolic blood pressure during pregnancy, and lighter newborns (P <0.001) than pregnant women in the control group. The GH group was older, had a higher BMI value before pregnancy, and had higher systolic and diastolic blood pressure during pregnancy (P <0.001) than the control group. The GDM group was older and had a higher BMI value before pregnancy, higher systolic and diastolic blood pressure during pregnancy, and heavier newborns (P <0.001) than the control group.
Table 3 Demographic and clinical characteristics of the patients and healthy controls
Criteria
|
Controls(n=1551)
|
PE (n=232)
|
GH (n=59)
|
GDM (n=319)
|
P-value†
|
P-value‡
|
P-value§
|
Age (years)
|
29.69±4.6
|
30.33±4.87
|
32.23±6.15
|
30.69±4.85
|
0.057
|
0.003
|
0.001
|
Height(cm)
|
163.26±5.03
|
162.35±5.15
|
162.14±5.77
|
162.89±4.9
|
0.011
|
0.1
|
0.232
|
BMI (kg/m2)
|
22.11±3.55
|
24.04±4.16
|
24.62±4.08
|
23.62±4.31
|
<0.001
|
<0.001
|
<0.001
|
Systolic blood pressure(mm Hg)
|
110.81±8.74
|
131.6±23.14
|
130.81±17.59
|
113.45±9.79
|
<0.001
|
<0.001
|
<0.001
|
Diastolic blood pressure(mm Hg)
|
70.21±7.06
|
84.39±15.32
|
84.98±14.08
|
72.09±8.25
|
<0.001
|
<0.001
|
<0.001
|
Birthweight (g)
|
3417.79±561.25
|
3001.18±834.5
|
3438.79±366.71
|
3562.72±450.69
|
<0.001
|
0.832
|
0.002
|
Data are expressed as the mean ± SEM. BMI, body mass index. †indicates comparison between the control and PE groups; ‡indicates comparison between the control and GH groups; §indicates comparison between the control and GDM groups.
Tables 4-6 show the correlation analysis results of the +936C/T and -634G/C polymorphisms with PE, GH and GDM. Table 4 summarizes the distribution of the +936C/T and -634G/C alleles and genotypes in the dominant mode [(GC+CC) vs GG] and recessive mode [CC vs (GC+GG)] in the control group and the PE group (severe PE (sPE) and mild PE (mPE)). In addition, the samples in the control group and PE group were divided into Han, Uyghur and Hui ethnic groups, and the distributions of the two SNP alleles and genotypes among the different ethnic groups were evaluated. After uncorrected chi-square test analysis, the allele frequency distributions of +936C/T and -634G/C showed no significant differences between the case group and the control group. The genotype distribution analysis was conducted using the dominant mode [(GC + CC) vs GG] and recessive mode [CC vs (GC + GG)] genetic patterns, and the results were also not significantly different between the case group and the control group. The results are shown in Table 4. The same method was used to analyse the correlations between the two SNPs and GH and GDM, and the results were not statistically significant (Table 5 and Table 6). Correlations were corrected for age, BMI, and ethnicity (results not shown), although the results were still not statistically significant.
Table 4 Correlations between the VEGF +936C/T and -634G/C genetic polymorphisms and PE risk
Samples(N)/ Different Models
|
VEGF (+936C/T) rs3025039
|
VEGF (-634G/C) rs2010963
|
Allele(N)
|
Dominant(N)
|
Recessive(N)
|
Allele(N)
|
Dominant(N)
|
Recessive(N)
|
Allele/Genotype
|
T
|
C
|
CT+TT
|
CC
|
TT
|
CT+CC
|
C
|
G
|
GC+CC
|
GG
|
CC
|
GC+GG
|
Control (1551)
|
515
|
2587
|
474
|
1077
|
41
|
1510
|
1188
|
1914
|
960
|
591
|
228
|
1323
|
PE (232)
|
65
|
399
|
60
|
172
|
5
|
227
|
183
|
281
|
149
|
83
|
34
|
198
|
OR (95% CIs);P
|
0.818(0.619-1.081);0.158
|
0.793(0.58-1.084);0.145
|
0.811(0.317-2.074);0.662
|
1.049(0.859-1.281);0.637
|
1.105(0.829-1.473);0.495
|
0.996(0.675-1.472);0.986
|
sPE (163)
|
46
|
280
|
44
|
119
|
2
|
161
|
131
|
195
|
109
|
54
|
22
|
141
|
OR (95% CIs);P
|
0.825(0.596-1.143);0.247
|
0.84(0.585-1.207);0.345
|
0.458(0.11-1.909);0.403
|
1.082(0.857-1.366);0.506
|
1.243(0.883-1.749);0.212
|
0.905(0.565-1.45);0.679
|
mPE (69)
|
19
|
119
|
16
|
53
|
3
|
66
|
52
|
86
|
40
|
29
|
12
|
57
|
OR (95% CIs);P
|
0.802(0.49-1.314);0.38
|
0.686(0.388-1.212);0.192
|
1.674(0.505-5.546);0.394
|
0.974(0.685-1.385);0.884
|
0.849(0.521-1.385);0.512
|
1.222(0.645-2.313);0.538
|
Han
|
Control (977)
|
354
|
1600
|
323
|
654
|
31
|
946
|
789
|
1165
|
629
|
348
|
160
|
817
|
PE (96)
|
28
|
164
|
26
|
70
|
2
|
94
|
84
|
108
|
69
|
27
|
15
|
81
|
OR (95% CIs);P
|
0.772(0.509-1.171);0.222
|
0.752(0.47-1.203);0.233
|
0.649(0.153-2.756);0.779
|
1.148(0.852-1.549);0.364
|
1.414(0.889-2.248);0.142
|
0.946(0.531-1.683);0.849
|
Uighur
|
Control (323)
|
89
|
557
|
84
|
239
|
5
|
318
|
214
|
432
|
177
|
146
|
37
|
286
|
PE (74)
|
18
|
130
|
17
|
57
|
1
|
73
|
47
|
101
|
40
|
34
|
7
|
67
|
OR (95% CIs);P
|
0.867(0.504-1.489);0.604
|
0.849(0.468-1.54);0.589
|
0.871(0.1-7.57);0.689*
|
0.939(0.641-1.378);0.749
|
0.97(0.584-1.611);0.908
|
0.808(0.345-1.89);0.622
|
Hui
|
Control (144)
|
44
|
244
|
41
|
103
|
3
|
141
|
107
|
181
|
91
|
53
|
16
|
128
|
PE (21)
|
6
|
36
|
6
|
15
|
0
|
21
|
20
|
22
|
14
|
7
|
6
|
15
|
OR (95% CIs);P
|
0.924(0.368-2.324);0.867
|
1.005(0.365-2.769);0.992
|
1.149(1.083-1.219);0.663*
|
1.538(0.802-2.949);0.193
|
1.165(0.442-3.068);0.757
|
3.2(1.087-9.423);0.064
|
*Results of Fisher’s exact test
Table 5 Correlations between the VEGF +936C/T and -634G/C genetic polymorphisms and GH risk
Samples (N)/ Different Models
|
VEGF (+936C/T) rs3025039
|
VEGF (-634G/C) rs2010963
|
Allele(N)
|
Dominant(N)
|
Recessive(N)
|
Allele(N)
|
Dominant(N)
|
Recessive(N)
|
Allele/Genotype
|
T
|
C
|
CT+TT
|
CC
|
TT
|
CT+CC
|
C
|
G
|
GC+CC
|
GG
|
CC
|
GC+GG
|
Control (1551)
|
515
|
2587
|
474
|
1077
|
41
|
1510
|
1188
|
1914
|
960
|
591
|
228
|
1323
|
GH (58)
|
24
|
92
|
23
|
35
|
1
|
57
|
47
|
69
|
35
|
23
|
12
|
46
|
OR (95% CIs);P
|
0.978(0.777-1.232);0.852
|
0.993(0.764-1.29);0.957
|
0.826(0.367-1.859);0.644
|
0.965(0.809-1.151);0.692
|
1.007(0.786-1.291);0.954
|
0.856(0.599-1.223);0.392
|
Han
|
Control (977)
|
354
|
1600
|
323
|
654
|
31
|
946
|
789
|
1165
|
629
|
348
|
160
|
817
|
GH (28)
|
14
|
42
|
13
|
15
|
1
|
27
|
24
|
32
|
17
|
11
|
7
|
21
|
OR (95% CIs);P
|
1.507(0.814-2.789);0.189
|
1.755(0.825-3.732);0.139
|
1.13(0.149-8.586);1
|
1.107(0.647-1.894);0.709
|
0.855(0.396-1.846);0.69
|
1.702(0.712-4.071);0.342
|
Uighur
|
Control (323)
|
89
|
557
|
84
|
239
|
5
|
318
|
214
|
432
|
177
|
146
|
37
|
286
|
GH (15)
|
6
|
24
|
6
|
9
|
0
|
15
|
14
|
16
|
10
|
5
|
4
|
11
|
OR (95% CIs);P
|
1.565(0.622-3.935);0.49
|
1.897(0.656-5.489);0.368
|
1.047(1.023-1.072);0.796*
|
1.766(0.846-3.686);0.125
|
1.65(0.552-4.935);0.366
|
2.811(0.851-9.281);0.174
|
Hui
|
Control (144)
|
44
|
244
|
41
|
103
|
3
|
141
|
107
|
181
|
91
|
53
|
16
|
128
|
GH (8)
|
1
|
15
|
1
|
7
|
0
|
8
|
5
|
11
|
4
|
4
|
1
|
7
|
OR (95% CIs);P
|
0.37(0.048-2.87);0.53
|
0.359(0.043-3.009);0.564
|
1.057(1.017-1.098);0.849*
|
0.769(0.26-2.273);0.634
|
0.582(0.14-2.426);0.708
|
1.143(0.132-9.898);1
|
*Results of Fisher’s exact test
Table 6 Correlations between the VEGF +936C/T and -634G/C genetic polymorphisms and GDM risk
Samples (N)/ Different Models
|
VEGF (+936C/T) rs3025039
|
VEGF (-634G/C) rs2010963
|
Allele(N)
|
Dominant(N)
|
Recessive(N)
|
Allele(N)
|
Dominant(N)
|
Recessive(N)
|
Allele/Genotype
|
T
|
C
|
CT+TT
|
CC
|
TT
|
CT+CC
|
C
|
G
|
GC+CC
|
GG
|
CC
|
GC+GG
|
Control (1551)
|
515
|
2587
|
474
|
1077
|
41
|
1510
|
1188
|
1914
|
960
|
591
|
228
|
1323
|
GDM (319)
|
104
|
534
|
97
|
222
|
7
|
312
|
239
|
399
|
198
|
121
|
41
|
278
|
OR (95% CIs);P
|
1.31(0.828-2.074);0.247
|
1.493(0.873-2.555);0.141
|
0.646(0.087-4.78);0.991
|
1.097(0.752-1.601);0.629
|
0.937(0.548-1.601);0.811
|
1.514(0.79-2.902);0.209
|
Han
|
Control (977)
|
354
|
1600
|
323
|
654
|
31
|
946
|
789
|
1165
|
629
|
348
|
160
|
817
|
GDM (221)
|
78
|
364
|
73
|
148
|
5
|
216
|
170
|
272
|
143
|
78
|
27
|
194
|
OR (95% CIs);P
|
0.969(0.739-1.269);0.817
|
0.999(0.732-1.362);0.993
|
0.706(0.272-1.838);0.474
|
0.923(0.747-1.141);0.458
|
1.014(0.747-1.377);0.927
|
0.711(0.459-1.1);0.124
|
Uighur
|
Control (323)
|
89
|
557
|
84
|
239
|
5
|
318
|
214
|
432
|
177
|
146
|
37
|
286
|
GDM (46)
|
10
|
82
|
9
|
37
|
1
|
45
|
33
|
59
|
24
|
22
|
9
|
37
|
OR (95% CIs);P
|
0.763(0.381-1.527);0.444
|
0.692(0.321-1.494);0.347
|
1.413(0.161-12.374);1*
|
1.129(0.715-1.782);0.602
|
0.9(0.485-1.67);0.738
|
1.88(0.841-4.205);0.119
|
Hui
|
Control (144)
|
44
|
244
|
41
|
103
|
3
|
141
|
107
|
181
|
91
|
53
|
16
|
128
|
GDM (32)
|
9
|
55
|
8
|
24
|
1
|
31
|
24
|
40
|
21
|
11
|
3
|
29
|
OR (95% CIs);P
|
0.907(0.418-1.969);0.806
|
0.837(0.348-2.015);0.692
|
1.516(0.153-15.067);0.555*
|
1.015(0.58-1.776);0.959
|
1.112(0.497-2.485);0.796
|
0.828(0.226-3.029);1
|
*Results of Fisher’s exact test
Table S2 shows the distribution frequency of haplotypes among the control, mPE, sPE, GH and GDM groups. The CT haplotypes were identified as severe PE protective type and GH risk type. Since this is not a common haplotype (frequency <0.15), the results are not representative.