Congenital Myasthenic Syndrome (CMS)
Congenital myasthenic syndrome (CMS) is an inherited diseases 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 a 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.
Characteristics and Symptoms
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 COLQ (collagen-liketail subunit of asymmetric acetylcholinesterase) gene is associated to congenital masthenic syndrome in Devon Rex and Sphynx. Syndrome is inherited in a 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.
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.