Experimental follistatin precursor protein · Fact sheet
Follistatin-344
Also known as FS344 · FST344
Follistatin-344 is a precursor isoform associated with myostatin and activin signaling research. Small human gene-transfer trials do not establish the safety, dose or efficacy of a protein product labeled follistatin-344.
What is Follistatin-344?
FS344 is processed into a secreted follistatin form. Follistatin binds signaling proteins including activins and myostatin.
A viral vector expressing follistatin in muscle is a different intervention from administering purified or commercially labeled protein.
Benefits & claims
Interest centers on muscle size and function. Activin biology also intersects with reproductive hormone signaling.
What the evidence supports
- In the Becker trial, four participants improved their walking distance while two showed no improvement.
- The inclusion-body myositis study included an exercise component and compared a small treated group with matched untreated participants.
- These exploratory gene-transfer outcomes do not establish a protein injection regimen or reliable muscle enhancement.
Research areas
- Muscle disease gene transfer
- Myostatin/activin signaling
Dosage & frequency
No established human regimenThe reviewed sources do not establish a human treatment amount or frequency for Follistatin-344. Animal and laboratory exposures are not human regimens.
How to read these amounts
An approved regimen belongs to a specific product, indication, and population. A study regimen describes what researchers tested; it does not establish a prescription or a safe self-use protocol. Products, routes, and formulations are not interchangeable. A prescriber uses the full label and individual clinical circumstances.
Personal accounts may describe amounts, schedules and outcomes beyond clinical research. They do not establish a regimen. Read the reported experiences
Formulations, interactions & practical context
- Identity and pharmacology
- FS344 is processed into a secreted follistatin form. Follistatin binds signaling proteins including activins and myostatin.
Formulation differences
- Viral-vector doses measured in vector genomes are not milligram amounts of follistatin protein.
- FS344 precursor expression and processed follistatin protein are related but different interventions.
Interactions & precautions
- The reviewed sources do not establish a comprehensive human interaction profile for this exact substance or combination.
What is still unresolved
- Safety and efficacy of the isolated protein in humans
- Long-term endocrine effects
- Functional benefit beyond muscle size
Side effects & risks
- Follistatin interacts with activin-related reproductive signaling; effects cannot be assumed to remain in skeletal muscle.
- Six-person gene-transfer studies cannot establish rare harms, long-term safety or purity of a separate protein product.
This is a summary of the cited evidence, not a complete product label. A lack of human safety data does not establish safety.
Clinical research
Limited or unclear evidenceThe Becker muscular dystrophy and inclusion-body myositis trials each involved six treated people and gene transfer. They cannot establish benefit from a different protein formulation.
Studies
Six-person proof-of-principle gene-transfer study.
Six treated participants; exercise and matched-control limitations.
Review explaining FS344 processing and activin-related concerns.
Personal experiences
Reports describe what someone noticed. They cannot establish cause, typical results, or how often a side effect happens. Amounts and schedules describe the individual account, not an effective or safe dose. Product identity and strength may be unverified, and missing details are left explicit.
No attributable personal accounts were found in the sources reviewed.
Approval status
There is no FDA-approved follistatin-344 bodybuilding product. Early gene-transfer research is not approval of an isolated follistatin preparation.
No FDA-approved product for this entry
Approval covers the labeled product, use and population. A trial phase does not establish success; a stopped program is not ongoing research.
Open questions
- Safety and efficacy of the isolated protein in humans
- Long-term endocrine effects
- Functional benefit beyond muscle size
Summary
These exploratory gene-transfer outcomes do not establish a protein injection regimen or reliable muscle enhancement.
Sources
Medical evidence and regulatory sources are listed here. Personal reports are linked separately in the experiences section.
- pubmedFS344 gene transfer in Becker muscular dystrophy
Six-person proof-of-principle gene-transfer study.
- pubmedFollistatin gene therapy in inclusion-body myositis
Six treated participants; exercise and matched-control limitations.
- pubmedFollistatin gene-transfer research context
Review explaining FS344 processing and activin-related concerns.