These proof of principle studies showed that NT-3 significantly improved axonal regeneration and enhanced the myelination process in experimental models and in sural nerves from patients with CMT1A, improving neuropathy impairment score and reducing sensory deficit as well.20 However, a short serum half-life, high production costs, need for repeated dosing and discontinuation of the commercial availability of product were limitations that discouraged further clinical trials of subcutaneously injected NT-3. This evidence concerns the gene NTF3 and Charcot-Marie-Tooth disease type 1A.