Folliculin: A Surprising Molecular Brake in the Human Hair Follicle

Fostier et al (2026) reveal that folliculin (FLCN), traditionally a tumor suppressor in kidneys, acts as a negative regulator of hair follicle growth in humans. Their study shows that FLCN limits the anagen phase of hair growth by maintaining high mTORC1 activity, and its knockdown increases insulin-like GF-1 and decreases TGF-β2, promoting hair growth. This discovery suggests potential treatments for hair growth disorders, such as using FLCN antagonists for conditions like telogen effluvium. The study, though insightful, is based on a small sample size and requires further research to confirm these findings in broader clinical settings.