Devon Rex myopathy
Introduction
- Cause: hereditary condition with a suspected highly penetrant autosomal recessive mode of inheritance.
- Signs: generalized muscle weakness (especially dorsal cervical and thoracic limb girdle muscle groups), head bobbing, passive ventro-flexion of the head and neck, dorsal protrusion of the scapulae, fatigability, slightly high stepping gait, megaesophagus, low head carriage, "dog-begging" posture.
- Diagnosis: muscle biopsy and immunohistochemical staining for alpha-dystroglycan protein.
- Treatment: no specific treatment. Keep indoors. Feeding from a platform can be helpful. Small feeds are better than large meals.
- Prognosis: guarded, although mildly affected individuals can have a long happy life; severely affected individuals have poor quality of life and often die after choking on food.
Presenting signs
- Ventro-flexion of the neck with the chin tucked into the sternum.
- Generalized muscle weakness.
- Head bobbing or head nodding.
- High stepping gait.
- Dorsal protrusion of the scapulae .
- Fatigability.
- Megaesophagus Megaesophagus.
- Low head carriage.
- "Dog-begging" or "chipmunk" or "Meeercat" posture or periscoping.
Acute presentation
- Can develop upper airway obstruction due to accumulation of ingesta in the vicinity of the larynx.
Age predisposition
- Congenital, clinical signs first appear between 3 and 23 weeks of age.
Breed/Species predisposition
Special risks
- Anesthetic risks relating to neuromuscular weakness (risk of laryngeal, pharyngeal and intercostal muscle weakness). Normally they can be safely anesthetized for muscle biopsy under general anesthesia.
Pathogenesis
Etiology
- Hereditary condition with a suspected autosomal recessive mode of inheritance.
- A genome-wide association study and whole-genome sequencing suggested a causal variant for this entity was a c.1190G>A variant causing a cysteine to tyrosine substitution (p.Cys39Tyr) within the C-terminal domain of collagen-like tail subunit (single strand of homotrimer) of asymmetric acetylcholinesterase (COLQ).
- Alpha-dystroglycan expression, which is associated with COLQ anchorage at the motor endplate, has been shown to be deficient in affected cats.
Pathophysiology
- Results from a deficiency in alpha-dystroglycan protein expression which is an extracellular membrane-associated protein that binds to a variety of extracellular matrix proteins.
Timecourse
- Congenital, progressive onset between 3 and 23 weeks of age.
- Usually slowly progressive.
- Some individuals are much worse affected than others.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Abitbol M, Hitte C, Bossé P et al (2015) A COLQ missense mutation in Sphynx and Devon Rex cats with congenital myasthenic syndrome. PLoS ONE 10 (9), e0137019 PubMed.
- Gandolfi B, Grahn R A, Creighton E K et al (2015) COLQ variant associated with Devon Rex and Sphynx feline hereditary myopathy. Anim Genet 46 (6), 711-715 PubMed.
- Martin P T, Shelton G D, Dickinson P J et al (2008) Muscular dystrophy associated with alpha-dystroglycan deficiency in Sphynx and Devon Rex cats. Neuromuscul Disord 18 (12), 942-952 PubMed.
- Shelton G D, Sturges B K, Lyons L A et al (2007) Myopathy with tubulin-reactive inclusions in two cats. Acta Neuropathol 114 (5), 537-42 PubMed.
- Malik R, Mepstead K, Yang F et al (1993) Hereditary myopathy of Devon Rex cats. J Small Anim Pract 34 (11), 539-546 VetMedResource.
- Lievesley P, Gruffyd-Jones T (1989) Episodic weakness and collapse in cats. Vet Annu 29, 261-269 VetMedResource.