LGMD R1 Natural History Study

This natural history study follows people with Limb-Girdle Muscular Dystrophy type R1 (LGMD R1), a rare genetic muscle disease caused by mutations in the CAPN3 gene. It causes progressive weakness in the shoulder and hip muscles. The study uses MRI, muscle strength testing, and other assessments over time to track how the disease progresses, which will help researchers design future treatments and clinical trials. You may be eligible if: - You are between 12 and 50 years old - You have confirmed LGMD R1 with genetic testing (homozygous or compound heterozygous mutations in CAPN3) - You have muscle weakness consistent with LGMD R1 - You can walk 10 meters without assistive devices (ankle-foot orthotics are okay) - You are able to provide your own informed consent (adults must consent themselves) You may NOT be eligible if: - You have a contraindication to MRI (e.g., metal implants, severe claustrophobia) - You are unable to walk 10 meters independently - You are pregnant - You have a dominant (not recessive) form of CAPN3 mutation (LGMD D4) - You have another illness that would affect the test results Talk to your doctor to see if this trial is right for you.