Table 1.- Variants (SNPs) included in the PRS calculation
(Disease/Trait: Ulcerative_colitis)
rsID	Risk allele	Effect size
rs16940186	C	0.445
rs9268853	T	0.315
rs17085007	C	0.315
Effect size: LN(OR)

Table 2.- PRS Score distribution among populations and regions
(Disease/Trait: Ulcerative_colitis)
	count	mean	sd	se	lower.ci	upper.ci
Pyrenean regions
WEST	168	0.115	0.066	0.005	0.105	0.125
SOUTH	83	0.113	0.062	0.007	0.099	0.127
EAST	146	0.109	0.061	0.005	0.099	0.119
Populations
IBS	107	0.129	0.063	0.006	0.117	0.141
PIR	397	0.112	0.063	0.003	0.106	0.119

Table 3.- Pairwise t-test for PRS score among populations and regions
(Disease/Trait: Ulcerative_colitis)
group1	group2	n1	n2	p	p.signif	p.adj	p.adj.signif
IBS	PIR	107	397	0.0183	*	0.183	ns
IBS	WEST	107	168	0.0849	ns	0.849	ns
IBS	SOUTH	107	83	0.0895	ns	0.895	ns
IBS	EAST	107	146	0.0140	*	0.140	ns
WEST	SOUTH	168	83	0.7930	ns	1.000	ns
WEST	EAST	168	146	0.3770	ns	1.000	ns
SOUTH	EAST	83	146	0.6380	ns	1.000	ns
* p < .05, ** p < .01, *** p < .001

Table 4.- Chi-square test comparison of percentile counts on Pyrenean regions compared to Iberian peninsula population
(Disease/Trait: Ulcerative_colitis)
Percentile rank	PIR				WEST				SOUTH				EAST
	adj.std.val	p.value	sig.val		adj.std.val	p.value	sig.val		adj.std.val	p.value	sig.val		adj.std.val	p.value	sig.val
pct95	0.810	0.418	.	white	0.880	0.379	.	white	0.810	0.418	.	white	0.710	0.478	.	white
pct75.95	−1.950	0.051	.		−1.070	0.285	.	white	−1.950	0.051	.		−2.390	0.017	*
pct50.75	−1.240	0.215	.	white	−0.010	0.992	.	white	−1.240	0.215	.	white	−1.020	0.308	.	white
pct25.50	1.160	0.246	.	white	−0.610	0.542	.	white	1.160	0.246	.	white	0.640	0.522	.	white
pct25	1.540	0.124	.	white	1.410	0.159	.	white	1.540	0.124	.	white	2.210	0.027	*
adj.std.val: Adjusted standardized residuals value; p.value: P value; sig.val: statistical significance, * p < .05, ** p < .01, *** p < .001; red dash to bottom: lower counts than reference; green dash to up: upper counts than reference