<scp>12‐Month</scp> progression of motor and functional outcomes in congenital myotonic dystrophy

Background We aim to describe 12-mo functional and motor outcome performance in a cohort of participants with congenital myotonic dystrophy (CDM). Methods CDM performed the 6 Minute Walk Test (6MWT), 10 Meter Run, 4 Stair Climb, Grip Strength, Lip Force at baseline visits. Parents completed Vineland Adaptive Behavior Scale. Results Forty-seven participants, aged 0 13 y old, were enrolled. 6MWT, Climb >85% eligible participants. The only significant difference between mean was an improvement 6MWT children 3-6 old (P = .008). This age group also had largest % all other timed testing. In >7 y, slope change on tests decreased or plateaued, further reductions ≥10 y. Participants CTG repeat lengths <500 did not perform differently than those >1000. Conclusions most feasible measures. Our findings are consistent clinical profile prior cross-sectional data, helping establish reasonable expectations trajectories this population as well identifying points which therapeutic interventions may be best studied. Further study outcomes >10 <3 is warranted, but new information will assist planning trials population.