Gelsolin is a calcium-regulated, actin-modulating protein that binds to the plus ends of actin monomers and filaments,Porcinereventing monomer e, Xenopus/Amphibian,change. Gelsolin promotes the assembly of monomers into filaments (nucleation) as well as sever filaments already formed. Defects in gelsolin are the cause of amyloidosis type 5 (AMYL5), also known as familial amyloidosis Finnish type. AMYL5 is a hereditary generalized amyloidosis due to gelsolin amyloid deposition, and is typically characterized by cranial neuropathy and lattice corneal dystrophy. Most patients have modest involvement of internal organs, but severe systemic disease can develop in some individuals, causing peripheral polyneuropathy, amyloid cardiomyopathy, and nephrotic syndrome leading to renal failure.