Follistatin 344
An FS344 gene-therapy trial increased the six-minute walk in four of six people by 29 to 125 metres (PMID 25322757; checked 24 Aug 2026). They had Becker muscular dystrophy. Two did not improve. The paper reported no adverse effects. PPMD, NIH, Jesse's Journey, and TMA supported the work. The trial delivered FS344 cDNA into muscle with an AAV vector. It did not inject FS344 protein from a vial.
What identity does Follistatin 344 describe?
FS344 is a chain of 344 amino acids from one human follistatin splice form (PMID 25322757; checked 24 Aug 2026). Cells cut off a 29-amino-acid signal part. That step yields FS315 in the blood.
GSRS lists human FOLLISTATIN with 315 parts under UNII 506IY26H2I (GSRS; checked 24 Aug 2026). That code does not prove the ID of full-length or His-tagged FS344. This entry keeps no ID block.
What did the Becker gene-transfer trial measure?
The trial treated six people with AAV1.CMV.FS344 in both legs (PMID 25322757; checked 24 Aug 2026).
| Participant result | Change in 6-minute walk | Primary source | Checked |
|---|---|---|---|
| Improved | +58 m | PMID 25322757 | 24 Aug 2026 |
| Improved | +125 m | PMID 25322757 | 24 Aug 2026 |
| No meaningful improvement | No change | PMID 25322757 | 24 Aug 2026 |
| No meaningful improvement | -14 m | PMID 25322757 full text | 24 Aug 2026 |
| Improved | +108 m | PMID 25322757 | 24 Aug 2026 |
| Improved | +29 m | PMID 25322757 | 24 Aug 2026 |
| Trial support | PPMD; NIH Wellstone Center 5U54HD066409-05; Jesse's Journey; TMA | PMID 25322757 full text | 24 Aug 2026 |
| Disclosed interest | B.K. Kaspar: related IP, Milo Biotechnology equity, paid Milo consultant | PMID 25322757 full text | 24 Aug 2026 |
The paper also reports reduced fibrosis and more normal muscle fibres.
What did the inclusion-body-myositis trial measure?
Six treated people improved by a median 56.0 m per year in the six-minute walk (PMID 28279643; checked 24 Aug 2026). Eight matched controls lost 25.8 m per year. The test gave p = 0.01.
Each treated person also trained. The controls came from an outside matched group, not a random placebo group. The same support and Milo interest applied.
What safety findings did the gene-transfer papers record?
| Study | Accessible safety finding | Checked |
|---|---|---|
| PMID 25322757 | No significant adverse events; serum chemistry and hormone levels remained normal | 24 Aug 2026 |
| PMID 25322757 | One person had an early immune response to follistatin; anti-follistatin antibody stayed below 1:50 | 24 Aug 2026 |
| PMID 28279643 | No treatment-related adverse events or serious adverse events | 24 Aug 2026 |
| PMID 28279643 | Two people had unrelated falls; one had an unrelated bicycle accident | 24 Aug 2026 |
| PMID 28279643 | No serum chemistry or hormone abnormality; anti-follistatin antibody stayed below 1:50 | 24 Aug 2026 |
These findings belong to AAV gene transfer. They do not show the safety of FS344 protein given by itself.
What did testing find in products labelled Follistatin 344?
A lab tested 17 black-market products labelled Follistatin 344 or Follistatin 315 (PMID 31758732; checked 24 Aug 2026). Nine had follistatin. Some others had MGF or GHRP-2. All nine had His-tagged FS344 and many linked groups called oligomers.
| Field | Value | Primary source | Checked |
|---|---|---|---|
| Study support | WADA grant 18B09CR; Federal Ministry of the Interior of Germany | PMID 31758732 | 24 Aug 2026 |
The His tags let the paper tell these products from the follistatin made by the body.
What does evidence tier B mean here?
Human trials tested AAV with FS344 DNA. They did not give FS344 protein by itself. Tier B applies to this small gene-trial set (checked 24 Aug 2026).
What is the recorded EU status?
The EU Commission index has no exact entry for Follistatin 344 or FS344 (Union Register index; checked 24 Aug 2026). The EU field stays unclear.
When was Follistatin 344 first observed in a product?
PMID 31758732 came out in November 2019 and reports tests of 17 products. It supports 2019-11 as a by-date, not the exact month of sale (checked 24 Aug 2026).
What does this register entry cover?
This entry keeps FS344 gene transfer, mature FS315, and His-tagged products apart. It does not move safety or effect data from one to another. No full guide is live yet.