The Caenorhabditis elegans genome contains two clear homologs of human FBN1, fbn-1 and mua-3 (Culetto and Sattelle 2000; Bercher et al. 2001; Frand et al. 2005). MUA-3 localizes to hypodermal cells, to which body wall muscle adheres and which are required for adhesion of the hypodermis to the cuticle (Plenefisch et al. 2000; Bercher et al. 2001). A defect in mua-3 is characterized by progressive muscle detachment throughout larval development (Bercher et al. 2001). fbn-1 is required for proper molting, specifically during the L3/L4 molt and L4/young adult molt (Frand et al. 2005). Complete knockout of mua-3 is lethal, whereas fbn-1 knockdown mutants exhibit molting defects, sterility, larval lethality, and slow growth, and lay dead eggs (Bercher et al. 2001; Frand et al. 2005). Mutations in fbn-1 and mua-3 genes cause molting defects that can be attributed to defects in a tissue that is functionally equivalent to connective tissue in mammals (Bercher et al. 2001; Frand et al. 2005). This demonstrates that C. elegans fibrillin genes have a conserved role in maintaining connective tissue-like tissue integrity, as does human FBN1. The molting defects of these C. elegans mutants suggest that the mechanical strain of molting (shedding and rebuilding the exoskeleton) mimics Marfan syndrome pathology where weak connective tissue is torn.