Facioscapulohumeral Muscular Dystrophy (FSHD)

Diagnosis

A diagnosis of facioscapulohumeral muscular dystrophy (FSHD) is typically suspected based on a person’s pattern of muscle weakness, especially involving the face, shoulder blades, and upper arms, often with asymmetric involvement. Individuals with suspected FSHD should be evaluated by a neurologist or specialist in neuromuscular disorders.

The most reliable way to confirm a diagnosis is through genetic testing. For FSHD1, testing identifies a shortening (contraction) of the D4Z4 repeat region on chromosome 4. For FSHD2, additional testing may be needed to identify related genetic changes, such as variants in the SMCHD1 gene. Genetic testing can confirm the diagnosis in the vast majority of cases.

In some situations, especially when the diagnosis is unclear, additional tests may be used to support evaluation or rule out other conditions. These can include:

• Blood tests to measure creatine kinase (CK), which may be normal or mildly elevated
• Electromyography (EMG) to assess muscle activity
• Muscle biopsy, though this is now less commonly needed when genetic testing is available

Because FSHD can resemble other muscle or nerve disorders, an accurate diagnosis is important. Advances in genetic testing mean that individuals diagnosed many years ago may benefit from updated testing to confirm their diagnosis.

For more information, see Causes/Inheritance.

Additional reading

• Preston MK, Wang LH. Facioscapulohumeral Muscular Dystrophy. 1999 Mar 8 [Updated 2025 Jul 10]. In: Adam MP, Bick S, Mirzaa GM, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2026. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1443/
• Tawil R et al; Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology (AAN); Practice Issues Review Panel of the American Association of Neuromuscular & Electrodiagnostic Medicine. Evidence-based guideline summary: Evaluation, diagnosis, and management of facioscapulohumeral muscular dystrophy: Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the AAN and the Practice Issues Review Panel of the AANEM. Neurology. 2015 Jul 28;85(4):357-64. doi: 10.1212/WNL.0000000000001783.

Last reviewed April 2026.