In other species: taurine cattle , pig , chicken , rabbit , goat , Japanese quail , sheep , water buffalo

Categories: Muscle phene

Possibly relevant human trait(s) and/or gene(s)s (MIM numbers): 601788 (gene) , 614160 (trait)

Links to MONDO diseases:

• MONDO:0013598: myostatin-related muscle hypertrophy

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal

Considered a defect: no

Key variant known: yes

Year key variant first reported: 2007

Cross-species summary: Abnormal increase in muscular tissue caused entirely by enlargement of existing cells (in contrast to muscular hyperplasia, in which the abnormal increase in muscular tissue is due to the formation and growth of new, normal muscle cells)

Species-specific name: Hypermuscularity; gross muscle hypertrophy; 'bully' whippets

Species-specific description: In addition to the occurrence of natural variants for this trait, variants have been created artificially (e.g. Zou et al., 2015): Genetically-modifed organism; GMO.

Clinical features: Affected dogs show an unusual amount of muscularity, especially in the neck and legs. They are broad chested and typically don’t conform to the breed standard (slim, long neck, pointed snout) (Mosher et al., 2007). Dogs with a single copy of the mutation show a smaller degree of hypermuscularity are significantly faster than homozygous wild-type whippets (Mosher et al., 2007). Hence, being heterozygous for the mutation is considered performance enhancing. For whippets with a double copy of the mutation, there is little evidence about potential associated health risks. It has been anecdotally reported amongst breeders that affected whippets are otherwise generally healthy and only suffer from occasional muscle cramps and a distinctive overbite (Mosher et al., 2007).

IT thanks DVM student Lucas Anderson, who provided the basis of this contribution in May 2023.

Breed: Whippet.

Associated gene: