Patient case (clinical description): An 8-year-old boy is brought to the clinic by his parents because of weakness and difficulty of standing up from a sitting position. The mother is healthy but had a brother who died in his 20th after being disabled and using wheelchairs in the last few years of his life. Physical examination shows 3/5 lower extremity muscle strength and enlarged calf muscles. The other physical examination and vital signs are unremarkable. Muscle biopsy showed absence of dystrophin protein. The patient is diagnosed with DMD.

Patient's own account: I brought my  8-year-old son to the doctor's clinic. He was struggling to stand up from a chair for the past few days. My wife is healthy but she was pretty worried since his brother died in his 20s after being disabled and using a wheelchair for the last years of his life. The doctor did an exam which highlighted weakness in the leg muscles and unusually large calf muscles. The rest of the exam was fine, and his vitals were normal. My son did a muscle biopsy, and it showed that the protein important for muscle strength and function is missing. The doctor diagnosed him with Duchenne muscular dystrophy.

Clinical trial: Longitudinal Study of the Natural History of Duchenne Muscular Dystrophy (DMD)

Eligibility criteria:
DMD Subject Inclusion Criteria

          -  Affected subjects must be male and between the ages of 2 and 30

          -  Affected subjects between the ages of 2 and 4 must have a diagnosis of DMD confirmed
             by at least one the following OR have an older male sibling that meet at least one of
             the following criteria:

               -  Dystrophin immunofluorescence and/or immunoblot showing complete dystrophin
                  deficiency, and clinical picture consistent with typical Duchenne dystrophy OR

               -  Gene deletion test positive (missing one or more exons) in the central rod domain
                  exons 25-60) of dystrophin, where reading frame can be predicted as
                  'out-of-frame',and clinical picture consistent with typical Duchenne dystrophy.

               -  Complete dystrophin gene sequencing showing an alteration (point mutation,
                  duplication, other) that is expected to preclude production of the dystrophin
                  protein(i.e. nonsense mutation, deletion/duplication leading to a downstream stop
                  codon),with a typical clinical picture of DMD.

          -  Affected subjects between the ages of 5 and 30 must either fulfill the above criteria
             OR show evidence of a dystrophinopathy and clinical picture consistent with Duchenne
             Muscular Dystrophy

               -  Participants who have documented clinical symptoms referable to a
                  dystrophinopathy and direct support of the diagnosis by either (1) a positive DNA
                  analysis for dystrophin mutation, (2) a muscle biopsy demonstrating abnormal
                  dystrophin, or (3) an elevated CK (>5X normal), and X-linked pedigree and an
                  affected family member who meets either criterion (1) or (2) as described above.

        NOTE: Determination of the appropriate clinical symptoms consistent with DMD will generally
        be the responsibility of the clinician. At a minimum this will include progressive loss of
        function, with additional consideration for other clinical features such as a
        characteristic gait, a positive Gower sign and calf pseudohypertrophy. When immunostaining
        of muscle biopsy is used to determining case definition, the clinical reviewer (site PI)
        should confirm that appropriate testing has ruled out a secondary deficiency of dystrophin.
        Affected subjects that do not exhibit the above symptoms consistent with DMD should be
        excluded.

        o Muscle weakness prevalent by 5 years of age

        - Non-affected adult subjects must be Parent(s) or legal guardian(s) of an eligible
        affected subject.

        DMD Serum Biomarker Inclusion Criteria

          -  Participants must meet eligibility criteria for the DMD phenotyping portion of this
             study

          -  For the GC-treatment response cohort, participants must initiate GC treatment within
             the first year of study participation (i.e. between their first study visit and their
             one year follow-up visit)

        DMD Subject Exclusion Criteria

        For those subjects that confirm DMD diagnosis through a clinical picture consistent with
        DMD

          -  Steroid-naïve subjects ambulating past the 13th birthday

          -  Steroid users ambulating past the 16th birthday

          -  Subjects/families who are unwilling or unable to comply with the protocol study
             procedures or visits

        Controls Subject Inclusion Criteria

          -  Male sex

          -  Age 6-30 years

          -  Able to comply with functional testing instructions

        Control Serum Biomarker Inclusion criteria

          -  Participants must be male

          -  Participants must be free of DMD, other neuromuscular disease, or other significant
             concomitant illness

          -  Participant must be free of glucocorticoid therapy

        Control Subject Exclusion Criteria

          -  Musculoskeletal disease

          -  Musculoskeletal injury within 6 months of enrollment

          -  Other concomitant illness that precludes functional testing in the judgment of the
             investigator or clinical evaluator

          -  Completion of enrollment for age cohort
Male
Accepts Healthy Volunteers
Subject must be at least 2 Years old.
Subject must be at most 30 Years

Eligibility (NLI label): Entailment