Bob tail (short tail, brachyury)

 

Gene: T

Transmission: Autosomal dominant

For an autosomal dominant genetic disease, an animal must have at least one copy of the mutation in question to be at risk of developing the disease.  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.  One or both of the parents of an animal with the mutation has one or two copies of the mutation.  Animals that have one or two copies of the mutation can pass the mutation on to future generations.

Mutation: Substitution, T gene; c.295 C>G, p.(I63M), exon1

Medical system: Skeletal

Breeds: Australian Shepherd, Australian Stumpy Tailed Cattle Dog, Austrian Pinscher, Bourbonnais Pointer, Brazilian Terrier, Brittany, Croatian Sheepdog, Danish Swedish Farmdog, Jack Russell Terrier, Karelian Bear Dog, Miniature American Shepherd, Miniature Australian Shepherd, Mudi, Parson Russell Terrier, Pembroke Welsh Corgi, Polish Lowland Sheepdog, Pyrenean Shepherd, Russell Terrier, Savoy Sheepdog, Schipperke, Spanish Water Dog, Swedish Vallhund, Toy Australian Shepherd

Age of onset of symptoms: From birth

The T gene encodes a protein involved in the development of the mesoderm and responsible for the number of vertebrae in the posterior part of the body.  When there is a mutation in the T gene, the result is a short tail.  If the animal is heterozygous for the mutation it will have a shorter tail.  The tail can be absent (anury) or shortened (brachyury).  When there are two copies of the mutated gene, this situation is lethal to the embryo.  Therefore, breeding two dogs with a short tail (Bobtail) will decrease the size of litters.

 

References:

OMIA link: [0975-9615]

Dreger DL, Hooser BN, Hughes AM, et al. (2019) True Colors: Commercially-acquired morphological genotypes reveal hidden allele variation among dog breeds, informing both trait ancestry and breed potential. PLoS One 14:e0223995.  [pubmed/31658272]

Hytonen MK, Grall A, Hédan B, et al. (2009) Ancestral T-Box mutation is present in many, but not all, short-tailed dog breeds.  Journal of Heredity 100(2):236-240. [pubmed/18854372]

Haworth K, Putt W, Cattanach B, et al. (2001) Canine homolog of the T-box transcription factor T; failure of the protein to bind to its DNA target leads to a short-tail phenotype.  Mammalian Genome 12:212-218. [pubmed/11252170]