COL2A1 and chondrodysplasia: One exemplary type-II collagenopathy is the chondrodysplasia caused by the autosomal-dominant c.3508 GGT > AGT mutation in exon 50 of COL2A1, leading to a p.Gly1170Ser substitution in the C-terminal region of the procollagen-II triple-helical domain (Fig 1A) (Liu et al, 2005; Su et al, 2008).