CD44 and hearing loss disorder: Loss of this organization at either the collagenous or noncollagenous level causes hearing loss in mice and humans.5,27 Because the N-propeptide domain plays a role in the establishment of molecular interactions with several extracellular matrix molecules and cellular proteins such as heparan sulfate proteoglycans and calcium, its alteration might impair its binding affinity for these molecules.25,28 This could hamper interactions between cells and the surrounding extracellular matrix, as well as interactions between the diverse constituents of the extracellular matrix.