Unlike clEDS patients, Tnxb–/– mice did not show overt signs of joint hypermobility or ligamentous laxity (Egging et al., 2006), although tail and Achilles tendon displayed ultrastructural changes in collagen fibril density similar to observations in the skin (Mao et al., 2002). Here, TNXB is linked to Ehlers-Danlos syndrome due to tenascin-X deficiency.