In the subset of patients (n = 45) with both baseline ctDNA data and mutational analysis from tumour biopsies, there was good concordance: 82% of the known uveal melanoma-specific mutations in ctDNA were also found in tumour biopsies; for mutations in GNAQ/GNA11 the concordance was 85% (Supplementary Table 5), and 43 of 45 tumour samples (96%) had likely loss of one copy of BAP1 (see Methods). Here, GNA11 is linked to uveal melanoma.