Native American ancestry and breast cancer risk in Colombian and Mexican women: ruling out potential confounding through ancestry-informative markers

Table 1 Results from main, sensitivity and stratified instrumental variable analyses on the association between Colombian Native American ancestry and breast cancer risk

	Method¹	# IV	Exp. var.² (%)	OR	95% CI		p-val	Q p-val³	intercept p-val⁴
Main analysis
Two-sample MR	IVW	98	7.1	0.974	0.970	0.978	3.1 × 10^–40	> 0.99
Sensitivity analyses
Two-sample MR	Egger	98	7.1	0.983	0.950	1.017	0.33	> 0.99	0.60
Two-sample MR	WM	98	7.1	0.975	0.969	0.980	1.1 × 10^–20
HGDP as reference⁵	IVW	95	6.6	0.974	0.970	0.978	6.1 × 10^–37	> 0.99
Stratified analyses
BC diagnosed ≤ 45 y⁶	IVW	106	7.7	0.978	0.972	0.984	1.2 × 10^–13	> 0.99
Familial BC⁷	IVW	104	7.5	0.958	0.952	0.964	2.0 × 10^–41	0.98
ER-positive BC⁸	IVW	94	6.8	0.968	0.963	0.972	7.1 × 10^–43	> 0.99
ER-negative BC	IVW	111	8.1	0.988	0.981	0.995	1.1 × 10^–03	> 0.99
Triple-negative BC⁹	IVW	110	7.9	0.993	0.983	1.003	0.19	> 0.99

Bold values indicate that the probability value is below 0.05
¹IVW: Inverse variance weighted; Egger: MR-Egger regression; WM: weighted median estimates
²Exp. var.: Variance explained by the instrumental variables
³Cochran’s Q statistic p-values higher than 0.05 are suggestive of no instrument heterogeneity as a proxy for pleiotropy
⁴MR-Egger intercept p-values higher than 0.05 are consistent with no horizontal pleiotropy
⁵Individuals from the Human Genome Diversity Project were used instead of the 29 Native Americans from Colombia as the reference panel for estimation of global ancestry proportions
⁶Breast cancer diagnosed before the age of 45 years
⁷Breast cancer patients with first-degree relatives affected by breast and/or ovarian cancer
⁸Oestrogen receptor-positive breast cancer
⁹Oestrogen receptor-negative, progesterone receptor-negative and human epidermal growth factor receptor-negative breast cancer

ISSN: 1465-542X