DESCRIPTION
Facioscapulohumeral muscular dystrophy (FSHD) is autosomal dominant and the third most common muscular dystrophy and involves progressive weakness and wasting of the facial muscles (facio), and shoulder and upper arm (scapulohumeral) muscles. The weakness is often most evident in the muscles of the face, resulting in difficulty smiling and whistling, and reduced facial expression. The weakness in the shoulder muscles causes the scapula to protrude from the back (“winging of the scapula”). The muscles are typically affected asymmetrically, and with progression, the lower extremities, both proximal and distal, become involved.
The severity of the disease is highly variable, ranging from mildly to severely affected, with approximately 20% of individuals eventually requiring a wheelchair. Non-muscular manifestations include retinal vascular abnormalities which can result in significant loss of vision; however, only about 1% of individuals with FSHD experience visual acuity loss. Most people with FSHD will eventually develop high-frequency hearing loss, which is usually not noticeable, and only detected by audiogram. FSHD usually presents between the ages of 6 and 20 years, and life expectancy is not shortened. It is estimated that 4-5 people per 100,000 have FSHD. FSHD tends to progress slowly and affects males and females equally. There is currently no treatment or prevention of symptoms of FSHD. Clinical management is directed at surveillance to identify possible FSHD-related complications and to improve quality of life (e.g., assist devices, physical therapy, orthoses to improve mobility and prevent falls).
The most common form of FSHD (95%) is designated FSHD1, and the remaining 5% of individuals who don’t have FSHD1 are designated as FSHD2, which is clinically indistinguishable from FSHD1. If FSHMD1A testing is negative, testing for FSHD2, including D4Z4 methylation analysis and testing of the SMCHD1 gene should be considered.
POLICY
Genetic testing to confirm a diagnosis of facioscapulohumeral muscular dystrophy when clinical signs (e.g., weakness of facial, scapular stabilizer, and foot dorsiflexor muscles) are present is considered medically necessary.
Genetic testing to confirm a diagnosis of facioscapulohumeral muscular dystrophy in the absence of clinical signs (e.g., weakness of facial, scapular stabilizer, and foot dorsiflexor muscles) is considered investigational.
IMPORTANT REMINDERS
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ADDITIONAL INFORMATION
There is a lack of well-designed evidence-based studies in peer review journals to determine whether the genetic testing for facioscapulohumeral muscular dystrophy in individuals with no clinical signs of the disease would change the individual’s medical management. Further studies are needed to establish the clinical utility of these tests and the long-term follow-up of the individuals.
SOURCES
American Academy of Neurology; American Association of Neuromuscular and Electrodiagnostic Medicine. (2015, July; reaffirmed September 2021). Evidence-based guideline summary: evaluation, diagnosis, and management of facioscapulohumeral muscular dystrophy. Retrieved September 24, 2021 from http://www.aan.com.
BlueCross BlueShield Association. Evidence Positioning System. (3:2023). Genetic testing for facioscapulohumeral muscular dystrophy (2.04.105). Retrieved February 9, 2024 from http://www.evidencepositioningsystem.com. (16 articles and/or guidelines reviewed)
Konstantonis, D., Kekou, K., Papaefthymiou, P., Vastardis, H., Konstantoni, N., Athanasiou, M., et al. (2022). Orofacial muscle weakening in facioscapulohumeral muscular dystrophy (FSHD) patients. Children (Basel, Switzerland), 9 (1), 96, doi: 10.3390/children9010096. (Level 3 evidence)
Pastorello, E., Cao, M., & Trevisan, C. P. (2012). Atypical onset in a series of 122 cases with facioscapulohumeral muscular dystrophy. Clinical Neurology and Neurosurgery, 114 (3), 230-234. (Level 4 evidence)
Rieken, A., Bossler, A. D., Mathews, K. D., & Moore, S. A. (2021). CLIA laboratory testing for facioscapulohumeral dystrophy: A retrospective analysis. Neurology, 96 (7), e1054–e1062, doi: 10.1212/WNL.0000000000011412. (Level 4 evidence)
Statland, J., Donlin-Smith, C. M., Tapscott, S. J., van der Maarel, S., & Tawil, R. (2014). Multiplex screen of serum biomarkers in facioscapulohumeral muscular dystrophy. Journal of Neuromuscular Disease, 1, (2), 181-190. Abstract retrieved May 21, 2015 from PubMed database.
Winston, J., Duerden, L., Mort, M., Frayling, I., Rogers, M., & Upadhyaya, M. (2015). Identification of two novel SMCHD1 sequence variants in families with FSHD-like muscular dystrophy. European Journal of Human Genetics, 23, 67-71. (Level 5 evidence)
ORIGINAL EFFECTIVE DATE: 1/11/2014
MOST RECENT REVIEW DATE: 3/14/2024
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