Congenital muscular dystonia

From Cow
Congenital muscular dystonia type 2 (CMD2) in Belgian Blue calf[1]

Congenital muscular dystonia (hyperekplexia) is a rare autosomal recessive genetic disease of Belgian Blue calves characterised by neurological signs.

Affected newborn calves present with lateral recumbency, and when forced to walk, have a low head carriage. Auditory or visual stimulation of these calves often triggers transient muscle spasms which regress when left alone[2].

Diagnosis is based on histopathology and genotyping with high-density SNP panels[3].

A differential diagnosis would include other congenital myopathies such as congenital myoclonus, arthrogryposis multiplex, neuropathic hydrocephalus, progressive degenerative myeloencephalopathy and spinal muscular atrophy.

An unrelated pseudomyotonia has been reported in a Dutch Improved Red and White cross-breed calf with similar clinical features but with dissimilar histopathological features[4].

Muscular dystonia is an hereditary disease and euthanasia is usually required. Most calves do not survive due to the severity of the condition.

References

  1. Harvey RJ et al (2008) The genetics of hyperekplexia: more than startle! Trends Genet 24(9):439-447
  2. Gill JL et al (2012) Identification of congenital muscular dystonia 2 associated with an inherited GlyT2 defect in Belgian Blue cattle from the United Kingdom. Anim Genet 43(3):267-270
  3. Charlier C et al (2008) Highly effective SNP-based association mapping and management of recessive defects in livestock. Nat Genet 40(4):449-454
  4. Grünberg W et al (2010) Pseudomyotonia, a muscle function disorder associated with an inherited ATP2A1 (SERCA1) defect in a Dutch Improved Red and White cross-breed calf. Neuromuscul Disord 20(7):467-470