About FSHD

Facioscapulohumeral muscular dystrophy (FSHD) is a rare, progressive and disabling disease for which there are no approved treatments. The disease is characterized by progressive skeletal muscle loss that initially causes weakness in muscles in the face, shoulders, arms and trunk, and progresses to weakness throughout the lower body. Skeletal muscle weakness results in significant physical limitations, including an inability to smile and difficulty using arms for activities, with many patients ultimately becoming dependent upon the use of a wheelchair for daily mobility.

FSHD is caused by aberrant expression of DUX4 in skeletal muscle, resulting in the inappropriate presence of DUX4 protein. Normally, DUX4-driven gene expression is limited to early embryonic development, after which time the DUX4 gene is silenced. In patients with FSHD, the DUX4 gene is unsilenced as a result of a genetic mutation. The result is death of muscle and its replacement by fat, resulting in skeletal muscle weakness and progressive disability.

We are developing losmapimod as an oral therapeutic for the potential treatment of FSHD. Losmapimod is currently being evaluated in a Phase 3 clinical trial, which we refer to as the REACH study (NCT: NCT05397470).

Fulcrum’s clinical trial

For more information, email [email protected].

Expanded access policy

We understand the urgent need of patients with few treatment options to gain access to therapies in development. Our goal, when possible, is to allow access to our investigational therapies through multiple channels when doing so does not disrupt or slow the commercialization process. Learn more about our expanded access policy.

Facts about FSHD


  • The prevalence of FSHD in the United States is approximately 16,000 to 38,000 people*
  • Affects all ethnic groups with similar incidence and prevalence
  • Many patients ultimately become dependent on the use of a wheelchair


*Based on recent estimates of prevalence of 1/20,000 and 1/8,333 and U.S. population of 320 million