Type XI collagen is a fibrillary collagen. Type XI collagen is broadly distributed in articular
cartilage, testis, trachea, tendons, trabecular bone, skeletal muscle, placenta, lung,
and the neoepithelium of the brain. Type XI collagen is able to regulate fibrillogenesis
by maintaining the spacing and diameter of type II collagen fibrils, and a nucleator for
the fibrillogenesis of collagen types I and II. Mutations in type XI collagen are associated
with Stickler syndrome, Marshall syndrome, fibrochondrogenesis, otospondylomegaepiphyseal
dysplasia deafness, and Weissenbacher–Zweymüller syndrome. Type
XI collagen binds heparin, heparan sulfate, and dermatan sulfate. Currently there are no
biomarkers for type XI collagen.