Myostatin-related muscle hypertrophy

Alternate names

Muscle hypertrophy syndrome

Definition

Myostatin-related muscle hypertrophy is a rare condition characterized by reduced body fat and increased muscle size.

Epidemiology

The prevalence of this condition is unknown.

Cause

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.

Gene mutations

Mutations that reduce the production of functional myostatin lead to an overgrowth of muscle tissue.

Inheritance

• Myostatin-related muscle hypertrophy has a pattern of inheritance known as incomplete autosomal dominance.
• People with a mutation in both copies of the MSTN 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.

Signs and symptoms

• 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 any medical problems, and affected individuals are intellectually normal.

Diagnosis

• Skeletal muscle size in an individual with myostatin-related muscle hypertrophy is measured by ultrasound examination, DEXA, or MRI.
• Subcutaneous fat pad thickness is measured by ultrasound or with a caliper.
• MSTN is the only gene in which mutation is known to cause myostatin-related muscle hypertrophy.

Treatment

Myostatin-related muscle hypertrophy is not known to cause medical complications.

NIH genetic and rare disease info

• NIH info on Myostatin-related muscle hypertrophy

Myostatin-related muscle hypertrophy is a rare disease.

Myostatin-related muscle hypertrophy Resources
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