Myotonia congenita

 

Gene: CLCN1

Transmission: Autosomal recessive

For an autosomal recessive genetic disease an animal must have two copies of the mutation in question to be at risk of developing the disease.  Both parents of an affected animal must be carriers of at least one copy of the mutation.  Animals that have only one copy of the mutation are not at risk of developing the disease but are carrier animals that can pass the mutation on to future generations.

Mutations:

Mutation 1: Substitution, CLCN1 gene; c.1930+1 G>T, splicing error in intron 16, cat chromosome A2

Mutation 2 : Deletion, CLCN1 gene; p.(L143Q fs STOP 3)

Mutation 3: Substitution, CLCN1 gene; c.991 G>C, p.(A331P)

Medical systems: Muscular

Breed: Domestic Cat, Domestic Longhair, Domestic Shorthair

Age of onset of symptoms: During the development of ambulatory capacity, around 4 weeks of age.

Feline myotonia congenita (MC) is a genetic disease of the neuro-musculo-skeletal junction where the chloride channels in the skeletal muscle cells are defective.  This “channelopathy” is characterized by a persistence of voluntary muscle contraction to give a marked muscle hypertrophy.  Reduced stride length and restricted limb adduction decrease gait fluidity.  To date myotonia congenita caused by the identified mutation has been seen only in isolated domestic cat populations.  A DNA test for the mutation is available.

 

References:

OMIA link: [0698-9685]

Corrêa S, Basso RM, Cerri FM, et al. (2023) Hereditary myotonia in cats associated with a new homozygous missense variant p.Ala331Pro in the muscle chloride channel ClC-1. J Vet Intern Med. [pubmed/37668104]

Anderson H, Davison S, Lytle KM, et al. (2022) Genetic epidemiology of blood type, disease and trait variants, and genome-wide genetic diversity in over 11,000 domestic cats. PLoS Genet. 18(6):e1009804. [pubmed/35709088]

Woelfel C, Meurs K, Friedenberg S, et al. (2022) A novel mutation of the CLCN1 gene in a cat with myotonia congenita: Diagnosis and treatment. J Vet Intern Med. 36(4):1454-1459. [pubmed/35815860]

Gandolfi B, Daniel RJ, O’Brien DP, et al. (2014) A novel mutation in CLCN1 associated with feline myotonia congenita. PLoS One. 9(10):e109926. [pubmed/25356766]

 

Contributed by: Amélia Bricault and Anne-Sophie Corriveau Roy, Class of 2027, Faculté de médecine vétérinaire, Université de Montréal.   (Translation DWS).