The Kniest syndrome is a rare, genetic spondylometaepiphyseal dysplasia with approximately 200 known cases worldwide. It follows an autosomal dominant pattern of inheritance. Disproportionate short stature, progressive dysplasia of the axial and the extremity skeleton, a flat face and the inability of making a fist are typical characteristics. Thickening and impaired mobility of the joints may lead to the inability to walk. The joint cartilage contains numerous holes resembling Swiss cheese in histological examination. Moreover, myopia, blindness due to retinal detachment, hearing impairment, osteoporosis and cleft palate are common signs. Along with achondrogenesis, hypochondrogenesis, spondylo-epiphyseal dysplasia and Stickler syndrome, these various types of connective tissue disorders are also termed type II collagen disorders. The Kniest syndrome is frequently associated with deletions or splice mutations leading to functional loss of an allele.
Defects in secretion of type II collagen were identified as cause which are associated with mutations in the COL2A1 gene. Most structural defects described are in-frame mutations caused by small deletions or splice mutations.