FGFR3 and Miyoshi myopathy: This is illustrated by elegant molecular profiling of a patient with MM with t(4;14) expressing a mutated, constitutively active FGFR3 in which treatment with the FGFR3 inhibitor erdafitinib led to complete eradication of the FGFR3 mutated clone and its replacement by a preexisting clone with del17p, without measurable clinical benefit (Croucher et al.2023).