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Congenital Myasthenic Syndrome (CMS)
| Acronym: | CMS |
| Gene: | COLQ |
| Mutation: | c.1190G>A |
| Inheritance: | Autosomal recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Congenital myasthenic syndrome (CMS) is an inherited disease characterized by a defect in signal transmission at the neuromuscular junction. In the domestic cat, few inherited neuromuscular disorders have been reported. The disorder was initially named “spasticity”. This disease first reported in the Devon Rex breed in 1974 was further characterized by Malik and collaborators in 1993 who concluded to have primary muscular dystrophy. Even though primarily described in the Devon Rex breed, it also affects the Sphynx breed. Sphynx and Devon Rex breeds are genetically very close, because of the repeated use of Devon Rex cats in Sphynx breeding programs.
Clinically, skeletal muscle weakness and fatigue represent common, non-specific features of CMSs in humans and animals. In the first five months of their life, affected cats from the two breeds display a general muscle weakness with a more pronounced functional deficiency of limb-girdle and axial muscles resulting in severe locomotor difficulties, fatigability, dorsal protrusion of the scapulae, and passive ventroflexion of the head and neck.
A mutation in exon 15 of the COLQ (collagen-like tail subunit of asymmetric acetylcholinesterase) gene is associated with the congenital myasthenic syndrome in Devon Rex and Sphynx. The syndrome is inherited in an autosomal recessive manner. Cat carrying one copy of the mutated gene is heterozygous and will not show congenital myasthenic syndrome (CMS) symptoms. When mating two carriers (heterozygotes) at conception each kitten has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. The presently available DNA test will help owners avoid matings at risk.
Results Reported As
Test Result |
Interpretation of test result |
CLEAR |
Tested mutation was not detected in animal with „clear“ result. Animal tested as clear has wild-type allele in homozygous state (i.e. two pairs of healthy alleles). It will not develop disease caused by tested mutation.* It will pass only wild-type allele to its offspring. |
CARRIER |
Tested mutation was detected in animal with „carrier“ result. Animal tested as carrier has one wild-type and one mutation allele, it is in heterozygous state. It will not develop disease caused by tested mutation.* It can pass wild-type or mutation allele to its offspring. |
AFFECTED |
Tested mutation was detected in animal with „affected“ result. Animal tested as affected has two copies of mutation alleles affecting the gene. It is likely the animal will experience a genetic disorder due to this mutation.** It will pass only mutation allele to its offspring. |
*Test excludes only tested mutation but not possible unknown mutations or factors that can lead to similar condition/symptoms.
** Potential unknown mutations or multiple other factors can possibly affect the likelihood of experiencing a genetic disorder.
References:
Abitbol, M., Hitte, C., Bossé, P., Blanchard-Gutton, N., Thomas, A., Martignat, L., Blot, S., and Tiret, L. (2015). A COLQ Missense Mutation in Sphynx and Devon Rex Cats with Congenital Myasthenic Syndrome. PLoS ONE 10, e0137019.