In 2004, a German boy was diagnosed with a mutation in both copies of the myostatin-producing gene, making him considerably stronger than his peers. His mother, a former sprinter, has a mutation in one copy of the gene. An American boy born in 2005 was diagnosed with the same condition.
Human myostatin consists of two identical subunits, each consisting of 109 amino acid residues. Its total molecular weight is 25.0 kDa. It can be produced in genetically engineered E. coli or eukaryotic cells and the recombinant protein from both sources is commercially available. However, due to the unique manner by which the mature protein is processed, there is considerable doubt as to the effectiveness of myostatin generated in E. coli.
A 2007 NIH study in PLOS Genetics found a significant relationship in whippets between a myostatin mutation and racing performance. Whippets that were heterozygous 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, shorter legs, and thicker tails. 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 sighthounds 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).
In 2005, Lee showed that a two-week treatment of normal mice with soluble activin type IIB receptor, a molecule that is normally attached to cells and binds to myostatin, leads to a significantly increased muscle mass (up to 60%). It is thought that binding of myostatin to the soluble activin receptor prevents it from interacting with the cell-bound receptors.
It remains unclear whether long term treatment of muscular dystropy with myostatin inhibitors is beneficial: the depletion of muscle stem cells could worsen the disease later on.
As of 2005, no myostatin-inhibiting drugs for humans are on the market, but an antibody genetically engineered to neutralize myostatin was developed by New Jersey pharmaceutical company Wyeth. The inhibitor is called MYO-029 and recently underwent testing however the results have not yet been made public. Some athletes, eager to get their hands on such drugs, turn to the internet, where fake "myostatin blockers" are being sold.
Johns Hopkins University has developed a technique for detecting mutations in myostatin variants.