Loss of MBNL1-mediated retrograde BDNF signaling in the myotonic dystrophy brain.

Reduced brain volume including atrophy in grey and white matter is commonly seen in myotonic dystrophy type 1 (DM1). DM1 is caused by an expansion of CTG trinucleotide repeats in the 3' untranslated region (UTR) of the Dystrophia Myotonica Protein Kinase (DMPK) gene. Mutant DMPK mRNA containing expanded CUG RNA (DMPK-CUG) sequesters cytoplasmic MBNL1, resulting in morphological impairment.