Table 5.

Odds ratios corresponding to increasing numbers of risk variants of the four SNPs in the combined studies

	Family history of PBT, n (%)		Logistic regression
No of risk variants *
	Yes (n = 172)	No (n = 2003)	OR (95% CI)#	P-value &
0	21 (12.2)	420 (21.0)	1 (reference)
1	78 (45.3)	1189 (59.4)	1.32 (0.81–2.12)	0.276
2	57 (33.1)	366 (18.3)	2.98 (1.79–4.90)	6.5 × 10−6
3	16 (9.3)	28 (1.3)	11.41 (5.38–19.8)	1.0 × 10−7
2~3	73 (42.4)	394 (19.6)	3.72 (2.28–6.01)	1.5× 10−8
Total	172 (100)	2003 (100)	P trend < 1.0 × 10−8

Note: PBT, Primary brain tumor; OR, odds ratio; CI, confidence interval.

^*Risk genotypes were defined as the minor allele of the four SNPs as risk variants (PRMT8 rs17780102, STYK1 rs2418087, SPOP rs6504618 and SOX5 rs7305773). We set cases with zero risk variants as the reference group, OR = 1.

^#Adjusted for age, sex, and histology.

^&P values for trend (two-sided) were derived from Extended Mantel-Haenszel chi square for linear trend tests (df = 1).