A recent single-patient DMD trial using i.v. rAAV9 at 1.0 × 1014 vgs/kg expressing dCas9 linked to VP64 to activate expression of cortical dystrophin ended fatally.336 The patient, who was non-ambulatory and had advanced disease at the time of dosing, developed worsening cardiac function on day five and acute respiratory distress syndrome on day six post-dosing, resulting in cardiopulmonary arrest and death on day eight post-treatment. This evidence concerns the gene DMD and acute respiratory distress syndrome.