ITGB4 and junctional epidermolysis bullosa: In addition, other genes which are known to be involved in the etiology of JEB, such as integrin, alpha 6 (MIM *147556) (Ruzzi et al., 1997) and integrin, beta 4 (MIM *147557) (Vidal et al., 1995), may harbor heterozygous mutations that cause dental defects in the absence of skin blistering since homozygous patients with a number of different JEB sub-types present with enamel hypoplasia (Fine et al., 2008).