GPRC5D and plasma cell myeloma: As downregulations and mutations discussed here occur primarily under selection pressure of the respective treatment and, in part, different aberrations occur in a subclonal manner (45), with the lack of this evolutionary pressure, and on the background of clonal heterogeneity of myeloma, other subclones can grow out after subsequent lines of treatment, conveying, e.g., again substantial expression of CD38 or GPRC5D, which can, in the same way, be identified by RNA-sequencing.