Table 3. Association of SNPs in the antioxidant system genes SOD2 and GPX1 with Crohn’s disease clinical characteristics.

Locus		Ilealcolonic (L3)**		Rectal involvement		Colonic involvement		Responds to biologics
	SNP / Model	OR	P-value	OR	P-value	OR	P-value	OR	P-value
		(95% CI)		(95% CI)		(95% CI)		(95% CI)
SOD2 rs4880	AA	1.00		1.00		1.00		1.00
	GA	0.82	0.577	1.23	0.457	0.84	0.442	1.48	0.347
		(0.41–1.65)		(0.72–2.10)		(0.55–1.30)		(0.65–3.35)
	GG	0.71	0.422	2.08	0.026	1.74	0.059	1.08	0.890
		(0.31–1.63)		(1.09–3.96)		(0.98–3.10)		(0.37–3.10)
	A carrier* vs. GG	0.80	0.546	1.83	0.034	1.93	0.011	0.83	0.682
		(0.40–1.63)		(1.06–3.16)		(1.15–3.22)		(0.34–2.03)
GPX1rs1050450	GG*	1.00		1.00		1.00		1.00
	GA	2.70	0.003	1.01	0.965	0.86	0.132	1.57	0.26
		(1.39–5.24)		(0.62–1.63)		(0.57–1.30)		(0.72–3.43)
	AA	1.81	0.250	0.61	0.093	0.62	0.475	3.10	0.032
		(0.66–4.95)		(0.26–1.40)		(0.33–1.16)		(1.10–8.70)
	G carrier* vs. AA	1.17	0.750	0.60	0.196	0.66	0.175	2.42	0.071
		(0.44–3.10)		(0.27–1.34)		(0.37–1.20)		(0.96–6.10)

* Reference; phenotype reference categories were defined as in Table 1;

** Reference category is “colonic” location;

ORs and 95% CIs were calculated considering the recessive and codominant models, adjusted for gender and age;

Bold font indicates nominally significant results;

P-value cutoff = 0.00063 (after Bonferroni correction applied to 80 tests performed in the case-case analysis in the CD group);

SNPs were genotyped on the complementary DNA strand.