AAV9 U7snRNA Gene Therapy to Treat Boys With DMD Exon 2 Duplications.

Inclusion Criteria

• Age greater than 6 months and less than 14 years
• Confirmed duplication of exon 2 in the DMD gene using a clinically accepted technique that completely defines the mutation
• Pre-ambulant (not yet walking) or ambulant (as defined by the ability to walk 10 meters without assistance)
• Males of any ethnic group will be eligible
• Ability to cooperate with muscle testing
• In subjects age 4 and above, stable dose and regimen of corticosteroid therapy (prednisone, deflazacort, or their generic forms) for at least 12 weeks prior to gene transfer.

Exclusion Criteria

• Active viral infection based on clinical observations
• Symptoms or signs of cardiomyopathy, including:
• Dyspnea on exertion, pedal edema, shortness of breath upon lying flat, or rales at the base of the lungs
• Echocardiogram with ejection fraction below 40%
• Serological evidence of HIV infection, or Hepatitis B or C infection
• Diagnosis of (or ongoing treatment for) an autoimmune disease
• Persistent leukopenia or leukocytosis (WBC ≤ 3.5 K/µL or ≥ 20.0 K/µL) or an absolute neutrophil count < 1.5K/µL
• Concomitant illness or requirement for chronic drug treatment that in the opinion of the SI creates unnecessary risks for gene transfer
• AAV9 binding antibody titers ≥ 1: 400 as determined by ELISA immunoassay
• Abnormal laboratory values in the clinically significant range as listed in Table 7, based upon normal values in the Nationwide Children's Hospital Laboratory.