Genetic variations in the SMAD4 gene and gastric cancer susceptibility

Table 4 Frequency distributions of the combined genotypes of SMAD4 SNP3 and SNP5 between gastric cancers and controls n (%)

No. variant (protective) alleles of the combined genotypes1	Cases (n = 322)	Controls (n = 351)	P2	Adjusted OR (95% CI)3
0	138 (42.9)	127 (36.2)	< 0.001
1	167 (51.8)	166 (42.3)
2	17 (5.3)	54 (15.4)
3	0 (0.0)	4 (1.1)
Dichotomized groups
0-1	305 (94.7)	293 (83.5)	< 0.001	1.00
2-3	17 (5.3)	58 (16.5)		0.28 (0.16–0.49)

¹0-3 represent the number of variants within the combined genotypes (0 = no variant and 1-3 = 1-3 variants); the variant (protective) alleles used for the calculation were the SNP3 C and SNP5 G alleles;

²Two-sided χ² test for the frequency distribution;

³Odds ratios (ORs) were obtained from a logistic regression model with adjustment for age, sex, smoking status, and alcohol use. SNP: Single nucleotide polymorphism; CI: Confidence interval.