The goal of this natural history study is to capture the natural history of Duchenne Muscular Dystrophy (DMD) in children and adults in the United Kingdom. Children and adults with DMD will be invited to join.

The primary objective of the study is to collect longitudinal data on motor and respiratory function in DMD patients from childhood to adulthood.

The secondary objectives of the study include collection of longitudinal data on other aspects of natural history on DMD, including respiratory, cardiac and endocrine complications, neurodiversity (cognitive impairment, neuro-behavioural disorders such as ADHD and autism), changes to bone density and occurrence of fractures, changes to puberty, incidence of scoliosis, unplanned hospital admissions, and quality of life. The study will also collect information on ethnicity.

Participants will attend an annual or bi-annual neuromuscular clinic, and will have a series of assessments and questionnaires with the study team. These include: key medical data, physiotherapy data, respiratory assessments, Quality of Life questionnaires, and DMD questionnaires. Following assessments and questionnaire completion, data is input into the study's tailor-made National Neuromuscular Database.

This study will make use of the existing NorthStar network to collect a wider range of clinically relevant data from paediatric and adult DMD patients, to describe more completely the natural history of the disease in different domains and across different life stages and disease phases. Data will be collected using assessment techniques and outcome measures appropriate to the major phases of the disease, and which are in some cases not currently part of the standard of care for DMD in the UK. The National Neuromuscular Database will continue to be used to collect and store these data. This study will allow the network to continue to describe the current natural history in DMD prospectively, with more robust subject ascertainment and completeness. This will help meet the current need for contemporary natural history data for the evaluation of new therapies, and further research in DMD.

Inclusion Criteria:

• All patients with genetically confirmed diagnosis of Duchenne Muscular Dystrophy in the United Kingdom. Recruitment will also be possible in cases in whom the DMD diagnosis is made after a muscle biopsy even if the dystrophin gene variant is still being investigated.

Exclusion Criteria:

• Involvement in clinical trials is not an exclusion criterion nor having had surgical procedures, as this is an observational research study. The regular clinical data of patients in clinical trials will be acquired as part of the clinical follow up.
• Patients based outside of the United Kingdom.

DMD patients of all ages (both paediatric and adult) will be recruited into the study. No age limits or restrictions within the DMD population have been set for this study, as the study aims to capture the natural progression or DMD irrespective of the stage of the disease. All DMD patients in paediatric or adult clinical care will therefore be eligible to participate providing they have consented

Fully anonymised summary-level data can be made available on request for collaborations. The data dictionary is currently publicly available.

After the study has closed, a clinical study report, publications etc may be shared with researchers. Summary-level anonymised data can be requested, subject to approval.

Academic researchers may contact the study central research group to request collaboration, usage of assessments, summary level of data.