However, in urine exRNA, expression of the reference gene GTF2B6 tended to be higher in DM1 as compared to UA subjects, and normalization of DMPK expression to GTF2B in urine exRNA revealed DMPK levels in DM1 patients about half that in the UA group (Fig. 1b, c). Here, GTF2B is linked to myotonic dystrophy type 1.