These data establish protein misfolding as a causative basis for the effects of G267S and S227P substitutions in AMD and CL, respectively, and raise the possibility that the I169T and G202R substitutions may be polymorphisms or may increase susceptibility to disease.
Fibulin 5 secretion was significantly reduced (P<0.001) for four ARMD (p.G412E, p.G267S, p.I169 T, and p.Q124P) and two cutis laxa (p.S227P, p.C217R) mutations.
Histological analysis of skin sections from a cutis laxa patient with a homozygous S227P mutation showed a lack of fibulin-5 in the extracellular matrix and a concomitant disorganization of dermal elastic fibers.
Molecular study of the fibulin-5 (FBLN5) gene in a large consanguineous Turkish family with four patients affected by AR cutis laxa type I demonstrated the presence of a homozygous missense mutation (T998C) in the FBLN5 gene resulting in a serine-to-proline (S227P) substitution in the fourth calcium-binding epidermal growth factor-like domain of fibulin-5 protein.