Funded in part by Winn Feline Foundation grants (W10-014, W11-041), the George and Phyllis Miller Trust through Winn (MT08-015, MT13-010), and Winn participation in the Cat Health Network (D12FE-510).
An international team of geneticists and neurologists from University of Missouri, University of California-Davis, University of California-San Diego, University of Sydney and the University of Milan has recently discovered the recessive mutation causing a congenital muscle weakness (myopathy) in Devon Rex and Sphynx cats. The gene, COLQ, affected by the mutation leads to a congenital myasthenic syndrome (CMS) similar to humans. A recessive mutation requires two copies of the mutation to have disease.
Devon Rex was the breed most likely affected initially and then spread to Sphynx. Signs in affected cats are passive ventroflexion of the head and neck, head bobbing, scapulae protrusion, megaesophagus, generalized muscle weakness and fatigability. Prominent spinal curvature (lordosis) can occur and the affected cats usually die by two years of age due to secondary complications by asphyxiation due to choking on food or aspiration pneumonia. Onset of signs ranges from 3 to 23 weeks of age and then progresses slowly or remains unchanging.
Additionally, cats with moderate to severe disease show signs of generalized muscle weakness, especially following periods of exertion, stress or excitement. There will be other typical signs of a high-stepping forelimb gait, head bobbing and progressive dorsal protrusion of the scapulae (shoulders). As affected cats tire more with exercise, they will have a shortening of stride and superimposed tremor until they eventually collapse in sternal recumbency. Their head will rest on or alongside their front paws. They may also assume a characteristic position for this condition – “dog-begging or “chipmunk” style- with their front legs resting on a nearby convenient object.
The disease appears to be recognized world-wide. The condition was initially noted and reported in 1989 in the United Kingdom. A few years later in1993, presentations were detailed in Australia. Cats with the disease have been found in the USA and more recently across Europe. (VT)