Solbakken G, et al. - In myotonic dystrophy 1 (DM1) patients and in an age and gender matched control group, researchers examined fat infiltration and muscle size in trunk muscles and how fat infiltration and degree of atrophy in these muscles correlated with motor and respiratory function in DM1 patients. In 20 patients with genetically confirmed classic form of DM1, researchers measured fat infiltration and trunk muscle size by MRI and compared these cases with 20 healthy, age and gender matched controls. Compared to age and gender matched controls, trunk muscles in DM1 patients had significantly greater degrees of fat infiltration and reduced muscle size. In DM1 patients, fat infiltration was correlated with reduced muscle strength, mobility, balance and lung function; reduced muscle strength and lung function were related to muscle size. These findings are important for clinical disease management and may be useful in future intervention studies for additional outcome measures.