Diagnosing your patients with GNE myopathy

What to look for in a clinical evaluation1

Most muscle dystrophies like GNE myopathy have common features such as slowly progressive symmetrical weakness, making subtypes (already inherently rare) difficult to diagnose.

Identifying pattern of muscle weakness, inheritance, and unique phenotypic features can help narrow down the muscle dystrophy subtype. In addition, a genetic test can help confirm GNE myopathy.

The American Academy of Neurology (AAN) recommends a clinical approach to diagnosing a patient with a suspected progressive muscular dystrophy.

1. Determine pattern of muscle weakness

GNE myopathy is typically a distal myopathy

2. Determine likely inheritance pattern

GNE myopathy is autosomal recessive

3. Identify distinguishing features

Clinical features

  • Foot drop
  • Relative quadriceps-sparing

MRI “signature” pattern of muscle involvement

  • Considerable fatty-fibrous replacement of the short head of the biceps femoris muscle; comparably less of the gluteus minimus, tibialis anterior, gastrocnemius medialis, and extensor hallucis, digitorum longus, and soleus muscles
  • EMG can supplement CT or MRI

Rimmed vacuoles

  • A muscle biospy identified rimmed vacuoles and characteristic filamentous inclusions; inflammation is generally not present

Order genetic testing to help confirm diagnosis

A genetic test for GNE myopathy is free

Delayed and under-diagnosis in GNE myopathy

Diagnosing on a clinical basis may be difficult because GNE myopathy1,2

  • Has similar clinical presentations to limb-girdle muscular dystrophy (LGMD), Charcot-Marie-Tooth (CMT) disease, and other distal myopathies
  • May not be recognized with manual muscle testing in a neurological exam
  • Can yield minimal pathology via biopsy if the sample taken is of a lesser affected muscle
The variable quality of a biopsy, coupled with the likelihood of sampling a less-affected muscle like the deltoid or quadriceps, underscores the difficulty of finding conclusive pathology to diagnose GNE myopathy.

Importance of genetic testing for GNE myopathy

The AAN recommends genetic testing to confirm a diagnosis of any progressive muscular dystrophy, including GNE myopathy. In addition to informing long-term prognosis of the disease, an accurate diagnosis helps to1,3

  • Efficiently direct care
  • Eliminate the need for repeated testing
  • Help patients prepare and plan for their future

A timely diagnosis may also help to shape long-term prognosis, as potential treatments to slow progressive damage in people with GNE myopathy have reached an advanced clinical study phase. When potential treatment becomes available, a definitive GNE myopathy diagnosis will help to initiate treatment early, potentially slowing the conversion of muscle to fatty-fibrous tissue.3

Free genetic testing

Free genetic testing is available for your patients to check for mutations in the GNE gene.

  • Test results take about 2 weeks
  • Complimentary referral to a genetic counselor to address any patient questions or concerns by phone
Check to see if your patient has the mutated GNE gene that causes GNE myopathy.
Order a free genetic testOrder a free genetic test

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Learn about clinical studies in development for genetically confirmed patients
References: 1. American Academy of Neurology. Summary of evidence-based guideline for clinicians: evidence-based guideline: diagnosis and treatment of limb-girdle and distal muscular dystrophies. 2014. 2. Nishino I, Carrillo-Carrasco N, Argov Z. GNE myopathy: current update and future therapy. J Neurol Neurosurg Psychiatry. July 14, 2014:1-8. doi:10.1136/jnnp-2013-307051. 3. O’Ferrall, EK, Sinnreich, M. GNE-related myopathy. In: Pagon RA, Adam MP, Ardinger HH, et al, eds. GeneReviews®. Seattle, WA: University of Washington, Seattle, 2013. 4. National Institute of Neurological Disorders and Stroke. Charcot-Marie-Tooth disease fact sheet. http://www.ninds.nih.gov/disorders/charcot_marie_tooth/detail_charcot_marie_tooth.htm?css=print. Updated February 23, 2015. Accessed May 12, 2015. 5. Narayanaswami P, Weiss M, Selcen D, et al. Evidence-based guideline summary: diagnosis and treatment of limb-girdle and distal dystrophies: report of the guideline development subcommittee of the American Academy of Neurology and the Practice Issues Review Panel of the American Association of Neuromuscular & Electrodiagnostic Medicine. Neurology. 2014;83:1453-1463.