Peptide directoryReproductive

Follistatin

The protein that binds and silences activin and myostatin.

Where it comes from

Made in
Ovarian granulosa cells, pituitary, liver (which makes most of the blood level), muscle
Sent out by
Rises with glucagon and fasting from the liver; local in follicle and muscle
Acts on
  • Activin
  • Myostatin
  • GDF11 and some bone morphogenetic proteins

What it does

  • Limits FSH by neutralising activin in the pituitary
  • Frees muscle from myostatin: mice given extra follistatin grow enormous muscles
  • Raised in liver disease and in the fasting state

In medicine

  • No approved medicine. ACE-083, a follistatin-based protein injected into single muscles, raised the treated muscle by 16 per cent in the biceps in facioscapulohumeral dystrophy 1 and by 13 per cent in the tibialis anterior in Charcot-Marie-Tooth disease 2, with no consistent gain in function in either, and development stopped
  • Serum follistatin is a research marker of insulin resistance and of liver disease, not a test in use

Beyond the body’s own use

  • A follistatin gene therapy is given outside the usual regulation, promoted for muscle and for longevity. The published human evidence is one open-label trial: six men with Becker muscular dystrophy had the gene injected into both thighs, four walked further afterwards and two did not, and there was no control group 3. A registered safety study of a follistatin gene therapy has completed without posting results
  • A gene therapy given outside an approval is reviewed by no regulator for safety, effectiveness or quality, and cannot be undone once given
  • Gene and cell doping is prohibited in sport at all times, which covers follistatin gene transfer 4

Sources

  1. Statland et al., Randomized phase 2 study of ACE-083 in facioscapulohumeral muscular dystrophy, Muscle and Nerve 2022
  2. Thomas et al., Randomized phase 2 study of ACE-083 in patients with Charcot-Marie-Tooth disease, Neurology 2022
  3. Mendell et al., A phase 1/2a follistatin gene therapy trial for Becker muscular dystrophy, Molecular Therapy 2015
  4. WADA Prohibited List, section M3, gene and cell doping

This card describes what a medicine is for and what the evidence says; it recommends nothing. Talk to your clinician about anything you read here.