Results from a 3-year Non-interventional, Observational Disease Monitoring Program in Adults with GNE Myopathy

J Neuromuscul Dis. 2021;8(2):225-234. doi: 10.3233/JND-200565.

Abstract

Background: GNE myopathy is a rare, autosomal recessive, muscle disease caused by mutations in GNE and is characterized by rimmed vacuoles on muscle biopsy and progressive distal to proximal muscle weakness.

Objective: Investigate the clinical presentation and progression of GNE myopathy.

Methods: The GNE Myopathy Disease Monitoring Program was an international, prospective, observational study in subjects with GNE myopathy. Muscle strength was assessed with hand-held dynamometry (HHD), with upper extremity (UE) and lower extremity (LE) composite scores reflecting upper and lower extremity muscle groups, respectively. The GNE myopathy-Functional Activity Scale (GNEM-FAS) was used to further assess impairment in mobility, upper extremity function, and self-care.

Results: Eighty-seven of 101 enrolled subjects completed the trial until study closure by the sponsor; 60 completed 36 months. Mean (SD) HHD UE composite score decreased from 34.3 kg (32.0) at baseline to 29.4 kg (32.6) kg at month 36 (LS mean change [95%CI]: -3.8 kg [-5.9, -1.7]; P = 0.0005). Mean (SD) HHD LE composite score decreased from 32.0 kg (34.1) at baseline to 25.5 kg (31.2) at month 36 (LS mean change [95%CI]: -4.9 [-7.7, -2.2]; P = 0.0005). GNEM-FAS scores were more severe at baseline in subjects who walked <200 meters versus ≥200 meters in 6 minutes; in both groups, GNEM-FAS total, mobility, UE, and self-care scores decreased from baseline through month 36.

Conclusions: These findings demonstrate progressive decline in muscle strength in GNE myopathy and provide insight into the appropriate tools to detect clinically meaningful changes in future GNE myopathy interventional trials.

Keywords: Myopathies; N-acetylneuraminic acid; muscle weakness; muscular diseases.

Publication types

  • Clinical Trial
  • Observational Study

MeSH terms

  • Adult
  • Bulgaria
  • Distal Myopathies / physiopathology*
  • Female
  • Humans
  • Lower Extremity / physiopathology
  • Male
  • Middle Aged
  • Muscle Strength
  • Muscle Weakness / physiopathology
  • Muscle, Skeletal / physiopathology
  • Prospective Studies
  • Young Adult

Supplementary concepts

  • Distal myopathy, Nonaka type