FGFR3 and cancer: In a recent study of 4,853 adult tumors, Helsten et al. reported that of the 7.1% of FGFR1-4-altered cancers in their cohort of 4853 tumors, 66% of the aberrations were due to copy number alterations, while 26% were single nucleotide variants, and 8% were gene rearrangements or fusions[34], and of 343 patients with an FGFR alteration, 89% of FGFR1 and 78% of FGFR4 alterations were amplifications compared with FGFR2 and FGFR3 with frequencies of 49% and 30%, respectively.