Performance Enhancement in Dogs
A 2007 NIH study in PLOS Genetics[13] found a significant relationship in whippets between a myostatin mutation and racing performance. Whippets that were hetrozygous for a 2 base pair deletion in myostatin were significantly over-represented in the top racing classes. Whippets with a homozygous deletion were apparently less able runners although their overall appearance was significantly more muscular. The 2 base pair mutation resulted in a truncated myostatin mRNA, likely resulting in an inactive form of myostatin.
Interestingly, whippets with the homozygous deletion also had an unusual body shape, with a broader head, pronounced overbite, and shorter legs. These whippets have also been called "bully whippets" by the breeding community due to their size, but not their temperament.
This particular mutation was not found in other muscular dog breeds such as boxers and mastiffs, nor was it found in other sight hounds such as greyhounds, Italian greyhounds, or Afghan hounds. The authors of the study suggest that myostatin mutation may not be desirable in greyhounds, the whippets nearest relative, because greyhound racing requires more significant endurance due to the longer races (900 meters for greyhounds vs. 300 meters for whippets).
http://en.wikipedia.org/wiki/Myostatin
