I'm surprised the FDA doesn't offer some sort of limited qualified approval in a case like this .... let the patient (or parents) decide if they'll accept the risk of taking the drug - without liability to the company or FDA.
There actually is a path. In the US a company can make a drug available before approval through an early access program. I am not sure but I believe it is always done through a clinical trial protocol. I know of several and one I am very familiar with is for a drug called Pirfenidone in the treatment of IPF. If you look in the description it indications as such. http://www.clinicaltrials.gov/ct2/show/NCT00080223 The company is allowed to be reimbursed but there are many restrictions such as it can't be marketed, its supposed to be priced to just recover costs, number of patients is limited, etc.
I believe the problem with SRPT is they claim they can't make enough drug (which raises its own set of questions).