CTLA4 and skin basal cell carcinoma: In terms of genes/loci common to both BCC and SCC, in addition to pigmentation genes (e.g. MC1R), overlapping pathways include immune response (e.g. rs2507999/HLA-B and rs231779/CTLA4) and telomere length (rs9419958/OBFC1) (Supplementary Material, Table S8).