Facioscapulohumeral muscular dystrophy (FSHSD) is one of the most common adult muscular dystrophies and is divided into types 1 and 2 based on genetic mutation. Clinically both FSHD types 1 and 2 demonstrate often asymmetric and progressive muscle weakness affecting initially the face, shoulder, and arms, followed by the distal and then proximal lower extremities later in the disease course. Approximately 95% of patients, termed FSHD1, have a deletion of a key number of repetitive elements on chromosome 4q35. The remaining 5%, termed FSHD2, have no deletion on chromosome 4q35. Nevertheless, both FSHD types 1 and 2 share a common downstream mechanism making it possible that future disease-directed therapies will be effective for both FSHD types 1 and 2.