Myotonic dystrophy (dystrophia myotonica - DM) exists in two forms, usually referred to as DM1 (type 1) and DM2 (type 2). Both conditions are genetic disorders but each affects a different gene. DM1 is the most common adult-onset muscular dystrophy, and is thought to affect at least 1 in 8,000 people worldwide. The aim is to facilitate a questionnaire based research study in order to better characterise and understand the disease in the UK. By maintaining a national registry this will help identify potential participants eligible for clinical trials in the future.