Epidermolysis bullosa simplex (EBS) is characterized by fragility of the skin (and mucosal epithelia in some instances) that results in non-scarring blisters and erosions caused by minor mechanical trauma. EBS is distinguished from other types of epidermolysis bullosa (EB) or non-EB skin fragility syndromes by the location of the blistering in relation to the dermal-epidermal junction. In EBS, blistering occurs within basal keratinocytes. The severity of blistering ranges from limited to hands and feet to widespread involvement. Additional features can include hyperkeratosis of the palms and soles (keratoderma), nail dystrophy, milia, and hyper- and/or hypopigmentation. Rare EBS subtypes have been associated with additional clinical features including pyloric atresia, muscular dystrophy, cardiomyopathy, and/or nephropathy.

Ectodermal dysplasia/skin fragility syndrome (EDSFS) is an autosomal recessive genodermatosis characterized by widespread skin fragility, alopecia, nail dystrophy, and focal keratoderma with painful fissures. Hypohidrosis and cheilitis are sometimes present (summary by Ersoy-Evans et al., 2006).

Striate palmoplantar keratoderma belongs to a group of skin diseases in which there is thickening of the skin on the palms and soles. The striate form is characterized by longitudinal hyperkeratotic lesions extending the length of each finger to the palm, and hyperkeratotic lesions are restricted to regions of the body where pressure and abrasion are greatest (summary by Hunt et al., 2001). Patients with diffuse or focal forms of keratoderma associated with mutation in the DSG1 gene have also been reported (Keren et al., 2005; Milingou et al., 2006). Genetic Heterogeneity of Keratosis Palmoplantaris Striata Type II PPKS (PPKS2; 612908) is caused by mutation in the DSP gene (125647) on chromosome 6. Type III PPKS (PPKS3; 607654) is caused by mutation in the keratin-1 gene (KRT1; 139350) on chromosome 12q. For a general phenotypic description and a discussion of genetic heterogeneity of palmoplantar keratoderma (PPK), see epidermolytic PPK (144200). Nitoiu et al. (2014) reviewed desmosome biology in cardiocutaneous syndromes and inherited skin disease, including discussion of the involvement of the DSG1 and DSP genes.

Generalized intermediate epidermolysis bullosa simplex-2B (EBS2B) is an autosomal dominant disorder of skin in which intraepidermal blistering occurs after minor mechanical trauma. Skin blistering is generalized, begins at birth, and is worsened by heat, humidity, and sweating. The tendency to blistering diminishes in adolescence, when it may become localized to hands and feet. Intermediate EBS has previously been known as the Koebner type (summary by Has et al., 2020). For a discussion of genetic heterogeneity of the subtypes of EBS, see EBS1A (131760). Reviews Has et al. (2020) reviewed characteristic features and molecular bases of the subtypes of epidermolysis bullosa, and provided a consensus reclassification of disorders with skin fragility.

Epidermolysis bullosa simplex (EBS) is characterized by fragility of the skin (and mucosal epithelia in some instances) that results in non-scarring blisters and erosions caused by minor mechanical trauma. EBS is distinguished from other types of epidermolysis bullosa (EB) or non-EB skin fragility syndromes by the location of the blistering in relation to the dermal-epidermal junction. In EBS, blistering occurs within basal keratinocytes. The severity of blistering ranges from limited to hands and feet to widespread involvement. Additional features can include hyperkeratosis of the palms and soles (keratoderma), nail dystrophy, milia, and hyper- and/or hypopigmentation. Rare EBS subtypes have been associated with additional clinical features including pyloric atresia, muscular dystrophy, cardiomyopathy, and/or nephropathy.