Table S1.

Scale for methodological quality assessment

Criteria	Score
1. Representativeness of cases
Gastric cancer diagnosed according to acknowledged criteria	2
Mentioned the diagnosed criteria but not specifically described	1
Not mentioned	0
2. Source of controls
Population or community-based	3
Hospital-based GC-free controls	2
Healthy volunteers without total description	1
GC-free controls with related diseases	0.5
Not described	0
3. Sample size
>300	2
200–300	1
>200	0
4. Quality control of genotyping methods
Repetition of partial/total tested samples with a different method	2
Repetition of partial/total tested samples with the same method	1
Not described	0
5. Hardy–Weinberg equilibrium (HWE)
Hardy–Weinberg equilibrium in control subjects	1
Hardy–Weinberg disequilibrium in control subjects	0

Abbreviation: GC, gastric cancer.