The purpose of this research study is to identify and study changes in muscle in people with facioscapulohumeral muscular dystrophy using magnetic resonance imaging and spectroscopy.

This research study is being done to study changes in muscle imaging over time in people with facioscapulohumeral muscular dystrophy (FSHD). Whole-body magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) will be used to evaluate skeletal muscle in study participants. This research is being done to assess how changes in muscle imaging correspond to muscle strength and function. Qualified participants will be asked to complete 5 study visits over 21 months. Each visit will include muscle strength and function testing in addition to the MRI/MRS scan. The investigators plan to use MRI and MRS in developing outcome measures that can be used in future clinical trials for FSHD.

Inclusion Criteria:

• Ability to give written informed consent for study participation (a parent or guardian will be asked to provide informed consent for participants younger than 18 years old)
• Confirmed diagnosis of FSHD through genetic testing (participants will be asked to provide copies of genetic testing results)

Exclusion Criteria:

• Any contraindication to MRI scanning
• Inability to complete a physical examination, including strength measurements

This study will include people with facioscapulohumeral muscular dystrophy confirmed through genetic testing.