The incidence of DMD is considered equal across racial and ethnic groups. At the start of the CINRG program, it was assumed by investigators that the aggregate subject populations of the participating US sites should closely mirror the racial and ethnic distribution of the US population.

DMD is an X-linked recessive disease affecting only males. However, female carriers of the disease can be symptomatic due to skewed X-inactivation, a secondary genetic event. We have opted to study the most commonly affected population, males, to ensure subject homogeneity. As such, there are no outreach programs planned for women in this study.

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 (ie. 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.

• 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.

Exclusion Criteria:

• Subjects may not be enrolled if their age at entry cohort has been filled.
• For steroid-naïve patients, ambulation past the 13th birthday
• For steroid users, ambulation past the 16th birthday