Exome sequencing identifies recurrent somatic mutations in EIF1AX and SF3B1 in uveal melanoma with disomy 3

Michael Zeschnigk and colleagues identify recurrent somatic mutations of EIF1AX and SF3B1 in uveal melanomas with disomy 3. The EIF1AX mutations specifically alter the N-terminal tail of the protein and were found exclusively in tumors lacking SF3B1 mutations. Gene expression profiles and chromosome 3 copy number divide uveal melanomas into two distinct classes correlating with prognosis 1 , 2 , 3 . Using exome sequencing, we identified recurrent somatic mutations in EIF1AX and SF3B1 , specifically occurring in uveal melanomas with disomy 3, which rarely metastasize. Targeted resequencing showed that 24 of 31 tumors with disomy 3 (77%) had mutations in either EIF1AX (15; 48%) or SF3B1 (9; 29%). Mutations were infrequent (2/35; 5.7%) in uveal melanomas with monosomy 3, which are associated with poor prognosis 2 . Resequencing of 13 uveal melanomas with partial monosomy 3 identified 8 tumors with a mutation in either SF3B1 (7; 54%) or EIF1AX (1; 8%). All EIF1AX mutations caused in-frame changes affecting the N terminus of the protein, whereas 17 of 19 SF3B1 mutations encoded an alteration of Arg625. Resequencing of ten uveal melanomas with disomy 3 that developed metastases identified SF3B1 mutations in three tumors, none of which targeted Arg625.