This research serves as a case study for preference studies at an early stage of drug development where there are no approved treatment options and little is known about potential treatment profiles.

For patients with myotonic dystrophy and mitochondrial disorders, ‘muscle strength’ and ‘energy and endurance (and daytime sleepiness)’ were the two symptoms for which patients would like to see improvement.

The ‘permanency (or temporality)’ of the risk was more relevant to patients when considering risk acceptability than the type of risk itself.

The majority of important treatment attributes were shared by patients with myotonic dystrophy and mitochondrial disorders, supporting the design of an elicitation experiment using a common survey.