1. 178 Ch/Ad CM cases (≤20 years) from M-SKIP database
59 Ch/Ad excluded because the MC1R gene was not sequenced
308 Ch/Ad cases with MC1R information
75 Ch/Ad cases excluded because there was no histopathological report available
233 Ch/Ad CM cases included in the study
For case-case analysis: 1:4 Ch/Ad case-A case matching from M-SKIP dataset (N=8582 adults)
For case-control analysis: 1:4 Ch/Ad case-A unaffected controls matching from M-SKIP dataset (N=5770 adults)
189 Ch/Ad CM cases (≤20 years) from IMI and European centers
USA: 17 Ch/Ad Ca; 68 A Ca; 112 A Co
Australia: 8 Ch/Ad Ca; 32 A Ca
Canada: 3 Ch/Ad Ca; 12 A Ca
Sweden: 31 Ch/Ad Ca; 58 A Ca;
58 A Co
Italy: 90 Ch/Ad Ca; 360 A Ca; 360 A Co
Greece: 6 Ch/Ad Ca; 72 A Ca;
72 A Co
Turkey: 5 Ch/Ad Ca
Serbia: 7 Ch/Ad Ca
The Netherlands: 66 A Ca; 66 A Co
Spain: 34 Ch/Ad Ca; 264 A Ca; 264 A Co
France: 32 Ch/Ad Ca
For case-case analysis: 932 A cases (≥35 years) matched by study (N=118 Ch/Ad cases) or by the closest geographical area (N=115 Ch/Ad cases)
 For case-control analysis: 932 A unaffected controls (≥35 years) matched by study (N=88 Ch/Ad cases) or by the closest geographical area (N=145 Ch/Ad cases)