Position of Arg→Cys substitutions in fibrillar collagens. The position of cysteine substitutions in the α1(I), α1(II), and α2(XI) collagens are illustrated. X-position changes are indicated below the line representing each molecule, whereas Y-position changes are indicated above the lines. Numbers represent the amino acid position within the helix. The resulting phenotypes are osteoarthritis (OA), spondyloepipheseal dysplasia (SED), SED congenita (SEDC), Stickler syndrome (SS), mild chondrodysplasia (MC), Stickler-like syndrome (SLS), classical Ehlers-Danlos syndrome (CEDS), and nonsyndromic deafness (DFN).