Table 3.

Associations of NAT1, NAT2, and EPXH1 polymorphisms with RA in African Americans based on cumulative smoking history; measures of gene-smoking interaction^*

Gene/polymorphism	Minor allele status	Smoking history	Cases (no.)	Controls (no.)	O.R.	95% C.I.	P-value
NAT1
rs11203942	Absent	Never, < 10py	195 (28.6)	76 (30.6)	1.00	----	----
	Present	Never, < 10py	295 (43.3)	125 (50.4)	0.91	(0.65, 1.28)	0.58
	Absent	≥ 10py	76 (11.2)	25 (10.1)	1.22	(0.72, 2.08)	0.46
	Present	≥ 10py	115 (16.9)	22 (8.9)	2.23	(1.30, 3.82)	0.004
					Pmult = 0.06 AP (95% CI) = 0.49 (0.12 to 0.87) Padd = 0.009
NAT2
rs9987109	Absent	Never, < 10py	245 (38.1)	93 (36.3)	1.00	----	----
	Present	Never, < 10py	220 (34.2)	116 (45.3)	0.73	(0.52, 1.01)	0.06
	Absent	≥ 10py	85 (13.2)	31 (12.1)	1.07	(0.66, 1.73)	0.79
	Present	≥ 10py	93 (14.5)	16 (6.3)	2.42	(1.34, 4.38)	0.003
					Pmult = 0.003 AP (95% CI) = 0.67 (0.39 to 0.95) Padd = 0.000003
rs1208	Absent	Never, < 10py	162 (23.6)	75 (28.7)	1.00	----	----
	Present	Never, < 10py	334 (48.8)	139 (53.3)	1.07	(0.76, 1.51)	0.69
	Absent	≥ 10py	60 (8.8)	26 (10.0)	1.10	(0.64, 1.90)	0.73
	Present	≥ 10py	129 (18.8)	21 (8.0)	3.03	(1.76, 5.23)	0.00006
					Pmult = 0.01 AP (95% CI) = 0.61 (0.34 to 0.89) Padd = 0.00001
rs721399	Absent	Never, < 10py	156 (24.1)	85 (33.9)	1.00	----	----
	Present	Never, < 10py	313 (48.3)	120 (47.8)	1.45	(1.03, 2.03)	0.03
	Absent	≥ 10py	63 (9.7)	9 (3.6)	4.13	(1.94, 8.78)	0.0002
	Present	≥ 10py	116 (17.9)	37 (14.7)	1.83	(1.15, 2.91)	0.01
					Pmult = 0.008 AP (95% CI)= −1.50 (−3.35 to 0.35) Padd = 0.11
EPXH1
rs2260863	Absent	Never, < 10py	142 (22.0)	74 (29.0)	1.00	----	----
	Present	Never, < 10py	320 (49.7)	135 (52.9)	1.23	(0.87, 1.74)	0.24
	Absent	≥ 10py	66 (10.2)	10 (3.9)	3.68	(1.77, 7.66)	0
	Present	≥ 10py	116 (18.0)	36 (14.1)	1.76	(1.09, 2.83)	0.02
					Pmult = 0.03 AP (95% CI) = −1.22 (−2.87 to 0.42) Padd = 0.15

^*NAT = N-acetyltransferase, EPXH1 = epoxide hydrolase; AP = attributable proportion due to interaction; ORs are age- and gender-adjusted