GT-repeat polymorphism in the heme oxygenase-1 gene promoter and the risk of carotid atherosclerosis related to arsenic exposure

Table 4 Combined effect of arsenic exposure and HO-1 genotype on the risk of carotid atherosclerosis.

Combination of arsenic exposure, μg/L and HO-1 genotype	Controls n (%)	Patients n (%)	Multivariate-adjusted OR (95% CI)	OR changes for carriers vs. non-carriers of the class S allele, %
Lanyang cohort ^a
≤ 50, Non-carriers of the class S allele	8 (3.1)	6 (2.4)	1.00	(Reference)
≤ 50, Carriers of the class S allele	20 (7.8)	12 (4.8)	0.60 (0.15-2.45)	-40.0
50-100, Non-carriers of the class S allele	21 (8.2)	24 (9.6)	1.49 (0.39-5.69)	(Reference)
50-100, Carriers of the class S allele	66 (25.8)	64 (25.6)	1.38 (0.40-4.80)	-7.4
100-300, Non-carriers of the class S allele	19 (7.4)	20 (8.0)	1.72 (0.44-6.70)	(Reference)
100-300, Carriers of the class S allele	60 (23.4)	61 (24.4)	1.37 (0.39-4.79)	-20.3
> 300, Non-carriers of the class S allele	17 (6.6)	22 (8.8)	1.48 (0.38-5.77)	(Reference)
> 300, Carriers of the class S allele	45 (17.6)	41 (16.4)	1.14 (0.32-4.08)	-23.0
LMN cohort ^b
≤ 300, Non-carriers of the class S allele	13 (7.9)	2 (1.7)	1.00	(Reference)
≤ 300, Carriers of the class S allele	39 (23.8)	10 (8.6)	0.49 (0.07-3.32)	-51.0
300-750, Non-carriers of the class S allele	22 (13.4)	20 (17.1)	1.13 (0.18-7.16)	(Reference)
300-750, Carriers of the class S allele	43 (26.2)	36 (30.8)	1.02 (0.17-6.10)	-9.7
> 750, Non-carriers of the class S allele	10 (6.1)	14 (12.0)	4.45 (0.64-30.93)	(Reference)
> 750, Carriers of the class S allele	37 (22.6)	35 (29.9)	1.09 (0.18-6.64)	-75.5*

OR: odds ratio; CI: confidence interval.
^a Adjusted for age, sex, logarithm triglyceride, total cholesterol, and hypertension history.
^b Adjusted for age, sex, hypertension history, and diabetes history.
Age, triglyceride, and cholesterol were defined as continuous variables in the regression models.
The class S allele denotes <27 GT repeats and L allele ≥27 GT repeats in the HO-1 gene promoter.
* p = 0.051 for the OR difference between carriers vs. non-carriers of the class S allele at arsenic exposure level >750 μg/L.

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