A Technique to Quantify Myotonia in Myotonic Dystrophy

Myotonic dystrophy type 1 (DM1) is an autosomal-dominant disorder related to expansion of a CTG repeat in the gene for DM protein kinase (DMPK) from the normal 5 to 37 repeats to between 50 and 4000 repeats. A second form of myotonic dystrophy, DM type 2 (DM2), is associated with a CCTG repeat expansion in the gene for zinc finger 9 (ZNF9). Myotonia involving various muscles, and typically the intrinsic hand muscles and the flexors of the fingers, is a common manifestation of myotonic dystrophies. To assess the feasibility of quantifying hand-muscle …