Short tail (Bobtail, brachyury) | Laboratoire de génétique vétérinaire

Short tail (Bobtail, Brachyury)

Gene: TBXT

Transmission: Autosomal dominant

The animal only has to have one copy of the mutation to be at risk of developing hypertrophic cardiomyopathy. Animals with two copies of the mutation generally have more severe symptoms and an earlier onset of the disease than animals with just one copy of the mutation. Offspring are potentially at risk of developing the disease if at least one parent carries the mutation.

Mutations:

Mutation 1 (American Bobtail, Manx, Pixiebob): Deletion, TBXT gene; c.998, del. T, p.(Leu332Pro frame shift STOP 22), exon7, chr.B2.

Mutation 2 (Manx, Pixiebob): Deletion-insertion, TBXT gene: c.[995_1011 dup, 1011_1114 del], p.(Ala338Ser frameshift STOP 21), exon7, chr.B2.

Mutation 3 (Manx, Pixiebob): Deletion, TBXT gene; c.1166 del.C, p.(Pro389Arg frameshift STOP 36, exon8, chr.B2.

Mutation 4 (American Bobtail, Manx, Pixiebob): Deletion, TBXT gene; c.1199, del.C, p.(Pro399Arg frameshift STOP 26), exon8, chr.B2.

Medical system: Skeletal

Breeds: American Bobtail, Manx, Pixie-bob

Age of onset of symptoms: Evident at birth.

Short tail (brachyury) is a defining feature of several cat breeds, including the Manx, American Bobtail and the Pixie-bob in western breeds, and the Kurilian Bobtail and Japanese Bobtail breeds in the far eastern breeds. The TBXT gene, previously called the T gene, codes for a protein called the T-box transcription factor T, also known as the Brachyury protein. Mutations in the TBXT gene, gene are responsible for short tail phenotypes in western breeds of cats. Short tail in cats is a dominant genetic trait that is evident at birth and can have variable in presentation, from absence of a tail (rumpy) to variable degrees of short tail (stumpy). Within the same litter will be animals with tails of normal length. The trait can be associated with additional developmental anomalies with variable penetration, including sacra agenesis or dysgenesis, absence of spinal cord in the sacral region, imperforate anus, incontinence for urine and or feces, and hindlimb paresis or paralysis. In the Manx cat there are four know mutations described within the TBXT gene that can give rise to the short tail trait. Interestingly, no cats that are homozygote for TBXT gene mutations have been seen, suggesting that double mutant animals (M/M) are embryonic lethal. The short tail seen in the Japanese Bobtail cat is the result of a mutation within the HES7 gene. It is strongly suspected that additional genetic mutations yet to be identified can also cause short tails in cats.

See also: Short tail, kinked (Japanese bobtail) (HES7 gene)

Interestingly, a mutation in the TBXT gene in dogs is responsible for the genetic short tail phenotype seen in several dog breeds, including the Australian Shepherd, Australian Stumpy Tail Cattle Dog, Doberman Pincher, Pembrooke Welsh Corgi, among others. The heredity is again dominant, although secondary phenotypic problems are not associated with the phenotype.

References:

OMIA link: [0975/9685]

Korzh V. (2023) Never-ending story of Brachyury: From short-tailed mice to tailless primates. Cells Dev 178:203896. [pubmed/38072067]

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. 16;18(6):e1009804. [pubmed/35709088]

Lyons LA, Creighton EK, Alhaddad H et al. (2016) Whole genome sequencing in cats, identifies new models for blindness in AIPL1 and somite segmentation in HES7. BMC Genomics. 17:265. [pubmed/27030474]

Xu X, Sun X, Hu XS, Zhuang Y et al. (2016) Whole Genome Sequencing Identifies a Missense Mutation in HES7 Associated with Short Tails in Asian Domestic Cats. Sci Rep. 6:31583. [pubmed/27560986]

Buckingham KJ, McMillin MJ, Brassil MM, et al. (2013) Multiple mutant T alleles cause haploinsufficiency of Brachyury and short tails in Manx cats. Mamm Genome 24:400-408. [pubmed/23949773]