The function of Fib3 is unknown, but related proteins, Fibulins2, 4, and 5, have been implicated in TGFβ binding to ECM [52] and both Fibulin5 [53] and Fibulin6 (hemicentin 1) [54] are also loci for macular degeneration risk. This evidence concerns the gene HMCN1 and macular degeneration.