Respiratory function will be assessed by a qualified and certified evaluator in each site. This is typically a respiratory therapist or physiotherapist. The participating patients will be instructed on the use of the site-based spirometer and a handheld nmd-1 device.
Patients will be asked to use the nmd-1 device. This device is used to monitor respiratory function at home once a week to have more data points to assess respiratory function decline.
At each study visit, the evaluator will download the data from the home device. The boy also will be asked to repeat the respiratory function test with the home device during each study visit.
Respiratory function measurements will include: