Genetic association study of RNF8 and BRDT variants with non-obstructive azoospermia in the Chinese Han population

Figures & data

Table 1. Clinical characteristics of the study population.

Characteristic	Controls (n = 368)^a	NOA (n = 361)^a	p Value
Body mass index (kg/m^2)	23.61 ± 3.53	23.09 ± 3.32	0.071
Right testicle volume (ml)	14.58 ± 2.65	8.90 ± 3.51	0.000
Left testicle volume (ml)	14.51 ± 2.70	8.95 ± 3.55	0.000
FSH	/	21.42 ± 19.88	/

^acontinuous variables were expressed as mean ± SD; NOA: non-obstructive azoospermia; /: no data available; FSH: follicle stimulating hormone. Student’s t test was used for the data analysis. Bold values indicated statistical significance (p < 0.05).

Table 2. Analysis of RNF8 and BRDT polymorphisms associated with the risk of NOA.

				MAF		HWE
Gene	SNP reference	Position	Nucleotide change	Controls	NOA	Controls	NOA	OR (95%CI)	p Value	PM
RNF8	rs104669	37354059	A > T	0.162	0.204	0.336	0.517	1.326 (1.015–1.733)	0.038	NS
	rs195379	37345704	T > C	0.119	0.090	0.802	0.513	0.738 (0.526–1.036)	0.078	NS
	rs195434	37360557	T > C	0.142	0.131	0.277	0.034	0.914 (0.677–1.235)	0.558	NS
	rs2284922	37349033	T > C	0.256	0.270	0.784	0.422	1.072 (0.848–1.354)	0.563	NS
	rs2284924	37327394	T > C	0.135	0.118	0.824	1	0.856 (0.628–1.167)	0.325	NS
	rs9380661	37331049	C > G	0.066	0.059	0.661	0.341	0.883 (0.576–1.354)	0.567	NS
	rs2269058	37324857	A > C	0.363	0.357	0.174	1	0.976 (0.787–1.209)	0.822	NS
	rs195432	37358022	C > A	0.086	0.081	0.326	0.019	0.930 (0.641–1.35)	0.704	NS
	rs169005	37341920	A > G	0.119	0.090	0.802	0.513	0.738 (0.526–1.036)	0.078	NS
BRDT	rs10783071	92428495	A > C	0.390	0.397	0.079	0.826	1.032 (0.836–1.274)	0.768	NS
	rs1156281	92442695	A > C	0.389	0.397	0.062	0.826	1.034 (0.837–1.276)	0.759	NS
	rs11165906	92440939	T > A	0.370	0.369	0.043	0.910	0.998 (0.806–1.236)	0.987	NS
	rs2183036	92477964	T > A	0.482	0.479	0.462	1	0.988 (0.804–1.215)	0.910	NS
	rs17576636	92447668	C > T	0.206	0.195	0.427	0.311	0.932 (0.721–1.205)	0.591	NS

NOA: non-obstructive azoospermia; MAF: minor allele frequency; HWE: Hardy-Weinberg equilibrium; P_M: corrected p value after Bonferroni correction; NS: no significance.

Table 3. The genotype distributions of rs104669 in the controls and the NOA cases.

			Controls	NOA
SNPs	Model	Genotype	N (frequency)	N (frequency)	OR (95%CI)	p Value	PM
rs104669	Codominant	AA	258(0.709)	230(0.639)	1
		AT	94(0.258)	113(0.314)	1.348[0.973–1.869]	0.072	NS
		TT	12(0.033)	17(0.047)	1.589[0.743–3.398]	0.229	NS
	Dominant	AA	258(0.709)	230(0.639)	1
		TT + AT	106(0.291)	130(0.361)	1.376[1.007–1.880]	0.045	NS
	Recessive	TT	12(0.033)	17(0.047)	1
		AT + AA	352(0.967)	343(0.953)	0.688[0.324–1.462]	0.328	NS

SNPs: single nucleotide polymorphisms; NOA: non-obstructive azoospermia; OR: odds ratio; Codominant model: DD versus Dd and DD versus dd; Dominant model: DD versus (Dd + dd); Recessive model: (DD + Dd) versus dd; d: minor allele; D: major allele. P_M: corrected p value after Bonferroni correction; NS: no significance.

Figure 1. Pairwise linkage disequilibrium (r²) in the study population.

Table 4. Haplotype distributions in 368 controls and 361 cases^a.

		Frequency
SNPs	Haplotype	Cases	Controls	p Value	OR
SNP1-9	ATCATCTCT	0.021	0.005	0.0086	4.052
SNP2-8	TCATCTC	0.110	0.070	0.0085	1.630
SNP2,3,4,5,6,8	CCATTC	0.029	0.021	0.2926	1.426
SNP2,3,4,5,6,7	TCATCA	0.081	0.102	0.1583	0.772
SNP7,8	AC	0.796	0.837	0.0428	0.759
SNP7,8	TC	0.124	0.077	0.0031	1.693
SNP7,8	TA	0.081	0.086	0.7041	0.930

^athe number 1–9 of the SNPs in the LD plot were rs2269058, rs2284924, rs9830661, rs169005, rs195379, rs2284922, rs104669, rs195432, and rs195434 of RNF8. SNPs: single nucleotide polymorphisms; OR: odds ratio. Bold values indicated statistical significance (p < 0.05).

Table 5. Associations of the selected polymorphisms with testis volume in the NOA patients.

		Testis volume
Gene	Genotype	<10 ml	≥10 ml	p Value	OR (95%CI)
RNF8	rs195432(C > A)	N = 163	N = 149	0.030
	CC	133	135		1
	CA	28	11		0.387(0.185–0.809)
	AA	2	3		1.478(0.243–8.986)
RNF8	rs195434(T > C)	N = 163	N = 149	0.025
	TT	124	115		1
	CT	29	33		1.227(0.701–2.147)
	CC	10	1		0.108(0.014–0.856)
RNF8	rs2284922(T > C)	N = 161	N = 149	0.034
	TT	78	91		1
	CT	64	50		0.67(0.415–1.080)
	CC	19	8		0.361(0.150–0.870)

The non-obstructive azoospermia (NOA) cases were divided into two groups, <10 ml and ≥10 ml according to testis volume of the patients. Chi-square test was used for data analysis. Fisher exact test was used where the number of genotype was less than five. Bold values indicated statistical significance (p < 0.05).

Table 6. The bivariate correlation between the number of copies of the minor allele at the SNPs and testis volume in the NOA patients and all the samples.

SNP	r1	r2	P1	P2
rs195432	−0.082	−0.001	0.147	0.963
rs195434	−0.073	−0.060	0.198	0.128
rs2284922	−0.105	−0.026	0.064	0.508

SNPs: single nucleotide polymorphisms; NOA: non-obstructive azoospermia; r1: correlation index of the two variates in the NOA patients; r2: correlation index of the two variates in all the samples; P1: p value in the NOA patients; P2: p value in all the samples.