DMPK and myotonic dystrophy type 1: On the other hand, the long-term, multisystemic overexpression of MBNL1 in wild-type mice and another DM1 mouse model, DM200+, which utilizes the doxycycline-dependent promoter that controls the expression of a transgene with 200 CTG repeats in the 3′ UTR of the DMPK gene, led to reduced body weight and increased mortality.32