Myostatin-related muscle hypertrophy
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Myostatin-related muscle hypertrophy (or myotonic hypertrophy) is a rare genetic condition characterized by reduced body fat and increased skeletal muscle size. Affected individuals have up to twice the usual amount of muscle mass in their bodies. They also tend to have increased muscle strength. Myostatin-related muscle hypertrophy is not known to cause medical problems, and affected individuals are intellectually normal. The prevalence of this condition is unknown.
Mutations in the MSTN gene cause myostatin-related muscle hypertrophy. The MSTN gene provides instructions for making a protein called myostatin, which is active in muscles used for movement (skeletal muscles) both before and after birth. This protein normally restrains muscle growth, ensuring that muscles do not grow too large. Mutations that reduce the production of functional myostatin lead to an overgrowth of muscle tissue. Myostatin-related muscle hypertrophy has a pattern of inheritance known as incomplete autosomal dominance. People with a mutation in both copies of the gene in each cell (homozygotes) have significantly increased muscle mass and strength. People with a mutation in one copy of the MSTN gene in each cell (heterozygotes) also have increased muscle bulk, but to a lesser degree.
Researchers at Guangzhou Institutes of Biomedicine and Health in China have edited the genome of beagles to create double the amount of muscle. Of the two beagles that were genetically modified, only one had increased muscle mass. The ultimate aim of this project is to be able to better treat a genetic neuromuscular disease (Parkinson's disease).
Besides beagles, genetic modification has also been done in pigs.
- Scientists created the first genetically engineered dogs — and they are bizarrely muscular, Business Insider, 21 October 2015, Kevin Lori
- Generation of gene-target dogs using CRISPR/Cas9 system
- Super-muscly pigs created by small genetic tweak