03INVMyotonic dystrophy type 1: A multisystemic disorder with remarkable clinical variability and burden

Myotonic dystrophy type 1 (DM1) is a complex, autosomal dominant disorder caused by a CTG repeat expansion in the DMPK gene. Though traditionally classified as a neuromuscular disease, DM1 is fundamentally a multisystemic disorder. It affects numerous organ systems including the heart, lungs, gastrointestinal (GI) tract, endocrine system, eyes, and central nervous system. Symptoms can be broadly divided into those due to skeletal muscle dysfunction—such as myotonia and weakness—and those arising from extra-muscular systems. Importantly, non-muscular manifestations often have a greater impact on daily functioning, independence, and quality of life than muscle symptoms. Recognizing DM1 as a multisystemic disease, rather than a purely neuromuscular one, is essential for effective diagnosis and care. This presentation aims to increase awareness of the broad and often underestimated systemic burden of DM1 and to highlight the need for early recognition, comprehensive screening, and tailored multidisciplinary care across all age groups. DM1 is one of the most variable disorders in medicine, with wide differences in age of onset, symptom severity, and organ involvement—even within the same family. This variability contributes to diagnostic delays and fragmented care. While muscle symptoms are often more visible, it is the gastrointestinal, urological, cognitive-behavioral, and fatigue-related symptoms that most disrupt daily life. These are frequently underdiagnosed, despite being central to patient morbidity. The burden also extends to families, who often provide complex daily care. Cardiac and pulmonary complications are major drivers of mortality in DM1. Conduction defects, arrhythmias, and sudden cardiac death, along with respiratory insufficiency and hypoventilation, pose serious and often under-recognized risks. Systematic screening and timely management of these complications are critical to improve survival. The initial diagnosis of DM1 may be made by a wide range of clinicians, depending on the patient’s presenting symptom: cardiologists, pulmonologists, ophthalmologists, gastroenterologists, neurologists, psychiatrists, or endocrinologists may be involved, as well as pediatricians or clinical geneticists in childhood-onset cases. A key challenge is that DM1 may present through any of its many systemic features, which means that if clinicians do not actively consider a multisystemic diagnosis, it may be overlooked. This presentation will provide an overview of the most burdensome systemic manifestations of DM1, their variability across age groups and individuals, and advocate for a proactive, comprehensive approach to screening, surveillance, and care. DM1 is not just a muscle disease but a multisystemic condition in which non-muscular symptoms often dominate the clinical picture. In particular, cardiac and respiratory complications are key contributors to mortality. The central message is: “What we do not ask, we do not know —and what we do not screen for, we do not detect.” Greater awareness, earlier recognition, and coordinated multidisciplinary care are essential to improving outcomes and quality of life for individuals with DM1 and their families.