Novel Metabolic Muscular Biomarkers in Pompe Disease - a Non-invasive Magnetic Resonance Exploratory Pilot Study.

Inclusion criteria Patients with PoD and McArdle disease: * age between 18-70 * Confirmed diagnosis: enzyme activity and/or genetic testing * body weight \> 40kg at screening * 6-minute walking distance \> 75m at screening (only PoD patients) * Sitting FCV ≥ 30% predicted (only PoD patients) * "Informed Consent" issued orally and in writing Healthy volunteers (controls): • age between 18-70 Exclusion criteria Patients with PoD and McArdle disease: * pregnancy (will be assessed prior to MRS measurements using a rapid pregnancy test) * Involvement of the respiratory musculature * claustrophobia * active participation in another clinical trial * metal devices or other magnetic material in or on the subjects body which will be hazardous for NMR investigation \[heart pacemaker, coronary stents and heart valves (in case these devices are not compatible with a 7T MRI), brain (aneurysm) clip, nerve stimulators, electrodes, ear implants, penile implants, colored contact lenses, patch to deliver medications through the skin, coiled spring intrauterine device, vascular filter for blood clots, orthodontic braces, shunt-spinal or ventricular, any metal implants (rods, joints, plates, pins, screws, nails, or clips), embolization coil, or any metal fragments or shrapnel in the body. Healthy volunteers (controls): * any known endocrine, metabolic or neurological disorder * special diets especially ketogenic or atkins diet * creatine supplementation * pregnancy (will be assessed prior to MRS measurements using a rapid pregnancy test) * claustrophobia * active participation in another clinical trial * metal devices or other magnetic material in or on the subjects body which will be hazardous for NMR investigation \[heart pacemaker, coronary stents and heart valves (in case these devices are not compatible with a 7T MRI), brain (aneurysm) clip, nerve stimulators, electrodes, ear implants, penile implants, colored contact lenses, patch to deliver medications through the skin, coiled spring intrauterine device, vascular filter for blood clots, orthodontic braces, shunt-spinal or ventricular, any metal implants (rods, joints, plates, pins, screws, nails, or clips), embolization coil, or any metal fragments or shrapnel in the body.