Myotonic Dystrophy Type 1 (DM1) is a rare genetic neuromuscular condition that can affect multiple organs and varies widely in how it presents. DM1 is the most common form of adult-onset muscular dystrophy, with an estimated prevalence of approximately 1-5 per 10,000 people. In Spain, the condition shows notable regional differences, making it especially important to understand its characteristics within the population. The aim of this study is to support a research initiative designed to better characterise DM1. We are developing a comprehensive national registry, collecting patient-reported information, clinical data and omics data that will improve our understanding of the disease and help identify individuals who may be eligible for clinical trials.