Association of C-reactive protein and complement factor H gene polymorphisms with risk of lupus nephritis in Chinese population

Table 1 Genotype and allele frequencies of C-reactive protein single nucleotide polymorphisms, n (%)

Genotype	LN	Normal	P value	Allele	LN	Normal	P value
rs1205 (C>T)
CC	53 (19.63)	49 (16.17)	0.469	C	245 (45.37)	254 (41.91)	0.239
CT	139 (51.48)	156 (51.49)		T	295 (54.63)	352 (58.09)
TT	78 (28.89)	98 (32.34)
rs3093077 (A>C)
AA	173 (64.07)	208 (68.65)	0.436	A	436 (80.74)	502 (82.84)	0.358
AC	90 (33.33)	86 (28.38)		C	104 (19.26)	104 (17.16)
CC	7 (2.59)	9 (2.97)
rs3091244 (C>T>A)
CC	153 (56.67)	180 (59.41)	0.9351	C	410 (75.93)	467 (77.06)	0.712
CT	23 (8.52)	28 (9.24)		T	29 (5.37)	36 (5.94)
CA	81 (30.00)	79 (26.07)		A	101 (18.70)	103 (17.00)
TT	1 (0.37)	1 (0.33)
TA	4 (1.48)	6 (1.98)
AA	8 (2.96)	9 (2.97)
rs1130864 (G>A)
GG	241 (89.26)	270 (89.11)	0.7971	G	509 (94.26)	572 (94.39)	0.924
GA	27 (10.00)	32 (10.56)		A	31 (5.74)	34 (5.61)
AA	2 (0.74)	1 (0.33)
rs1800947 (C>G)
CC	245 (90.74)	273 (90.10)	1.0001	C	515 (95.37)	575 (94.88)	0.703
CG	25 (9.26)	29 (9.57)		G	25 (4.63)	31 (5.12)
GG	0 (0.00)	1 (0.33)
rs2794521 (T>C)
TT	187 (69.26)	222 (73.27)	0.177	T	446 (82.59)	520 (85.81)	0.135
TC	72 (26.67)	76 (25.08)		C	94 (17.41)	86 (14.19)
CC	11 (4.07)	5 (1.65)

¹Fisher’s exact test; unmarked, Pearson’s chi-squared test.

LN: Lupus nephritis.

Table 2 Pairwise linkage disequilibrium analysis of C-reactive protein single nucleotide polymorphisms in healthy controls

r2\D'	rs3093077	rs1205	rs1130864	rs1800947	rs3091244	rs2794521
rs3093077		1.000	0.990	0.985	0.979	0.748
rs1205	0.278		0.999	0.999	0.984	1.000
rs1130864	0.012	0.082		0.986	1.000	0.974
rs1800947	0.011	0.039	0.003		0.993	0.986
rs3091244	0.675	0.360	0.212	0.014		0.996
rs2794521	0.019	0.229	0.009	0.009	0.044

D’ and r² are listed on the top right and lower left, respectively. Bold represents pairs with D’ values great than 0.8 and r² values great than 0.33.

Table 3 Association of C-reactive protein haplotypes with risk of lupus nephritis

CRP haplotype		SLE-freq (%, n = 270)	Normal-freq (%, n = 303)	χ2	Overall P value
H1	G G G G T A	17.8	16.7	3.293	0.655
H2	T A G C G A	4.3	5.1
H3	T A G G G A	50.2	52.8
H4	T G A G A A	5.4	5.6
H5	T G G G G A	4.1	5.1
H6	T G G G G G	16.6	13.7

Single nucleotide polymorphism order in the haplotypes is arranged according to their positions in the chromosome (rs3093077, rs1205, rs1130864, rs1800947, rs3091244, rs2794521). Only the significant haplotypes (frequency > 3.0%) are shown. CRP: C-reactive protein; SLE: Systemic lupus erythematosus.

Table 4 Genotype and allele frequencies of complement factor H single nucleotide polymorphisms, n (%)

Genotype	LN	Normal	P value	Allele	LN	Normal	P value
rs1061170 (T>C)
TT	235 (87.04)	258 (85.15)	0.2201	T	503 (93.15)	561 (92.57)	0.707
TC	33 (12.22)	45 (14.85)		C	37 (6.85)	45 (7.43)
CC	2 (0.74)	0 (0.00)
rs482934 (A>C)
AA	236 (87.41)	258 (85.15)	0.1891	A	504 (0.93)	561 (0.93)	0.617
AC	32 (11.85)	45 (14.85)		C	36 (0.07)	45 (0.07)
CC	2 (0.74)	0 (0.00)
rs1061147 (C>A)
CC	235 (87.04)	257 (84.82)	0.1941	C	503 (0.93)	560 (0.92)	0.63
CA	33 (12.22)	46 (15.18)		A	37 (0.07)	46 (0.08)
AA	2 (0.74)	0 (0.00)

¹Fisher’s exact test; unmarked, Pearson’s chi-squared test.

LN: Lupus nephritis.

Table 5 Pairwise linkage disequilibrium analysis of complement factor H single nucleotide polymorphisms in healthy controls

r2\D'	rs1061147	rs482934	rs1061170
rs1061147		0.976	1.000
rs482934	0.930		0.976
rs1061170	0.977	0.952

D’ and r² are listed on the top right and lower left, respectively. Bold represents pairs with D’ values great than 0.8 and r² values great than 0.33.

Table 6 Association of complement factor H haplotypes with risk of lupus nephritis

CRP Haplotype		LN-freq (%, n = 270)	Normal-freq (% n = 303)	χ2	Overall P value
H1	A C G	6.3	7.3	0.426	0.514
H2	C A A	93.3	92.2

SNP order in the haplotypes is arranged according to their positions in the chromosome.

CRP: C-reactive protein; LN: Lupus nephritis.

Table 7 Genotype frequencies of combined single nucleotide polymorphisms of C-reactive protein and complement factor H, n (%)

CRP-CFH genotype combination	LN	Normal	P value
rs1205 + rs1061170
CCTT	46 (17.10)	45 (14.85)	0.105
CCTC	7 (2.60)	4 (1.32)
CTTT	124 (46.10)	125 (41.25)
CTTC	14 (5.20)	31 (10.23)
TTTT	65 (24.16)	88 (29.04)
TTTC	13 (4.83)	10 (3.30)
rs3093077 + rs1061170
AATT	150 (56.39)	180 (59.80)	0.322
AATC	23 (8.65)	28 (9.30)
ACTT	81 (30.45)	71 (23.59)
ACTC	8 (3.01)	15 (4.98)
CCTT	4 (1.50)	7 (2.33)
rs3091244 + rs1061170
CCTT	133 (50.57)	155 (52.19)	0.756
CCTC	21 (7.98)	25 (8.42)
CTTT	21 (7.98)	25 (8.42)
CATT	71 (27.00)	64 (21.55)
CATC	9 (3.42)	15 (5.05)
TATT	4 (1.52)	6 (2.02)
AATT	4 (1.52)	7 (2.36)
rs1130864 + rs1061170
GGTT	208 (78.49)	228 (76.25)	0.772
GGTC	32 (12.08)	42 (14.05)
GATT	25 (9.43)	29 (9.70)
rs1800947 + rs1061170
CCTT	214 (80.75)	232 (77.85)	0.655
CCTC	30 (11.32)	41 (13.76)
CGTT	21 (7.92)	25 (8.39)
rs2794521 + rs1061170
TTTT	160 (59.93)	187 (61.92)	0.431
TTTC	26 (9.74)	35 (11.59)
TCTT	66 (24.72)	67 (22.19)
TCTC	6 (2.25)	9 (2.98)
CCTT	9 (3.37)	4 (1.32)

Pearson’s chi-squared test.

CRP: C-reactive protein; CFH: Complement factor H; LN: Lupus nephritis.