MedGen

Autosomal dominant epidermolytic hyperkeratosis-2A (EHK2A) is a skin disorder characterized by blistering, keratoderma, and erythroderma. Severity and body involvement show clinical heterogeneity (summary by Syder et al., 1994). While the neonatal presentation is often blistering and redness, the primary features of the disorder are hyperkeratosis (thickening of the uppermost layer of the epidermis, the stratum corneum) and blistering (summary by Chipev et al., 1994). For a discussion of genetic heterogeneity of epidermolytic hyperkeratosis, see EHK1 (113800). [from OMIM]

Autosomal recessive epidermolytic hyperkeratosis-2B (EHK2B) is a rare and clinically variable defect of cornification characterized by generalized erythema, erosions, scaling, and easily breaking blisters that become less frequent later in life, while hyperkeratosis increases (summary by Terheyden et al., 2009). For a discussion of genetic heterogeneity of epidermolytic hyperkeratosis, see EHK1 (113800). [from OMIM]

Annular epidermolytic ichthyosis-1 (AEI1) is characterized by the development of widespread erythematous blistering in the neonatal period or early childhood that subsides over time. Patients later show hyperkeratotic lichenified plaques over flexural and extensor surfaces, and experience episodic annular and polycyclic erythematous plaques over the trunk and proximal extremities (Joh et al., 1997; Suga et al., 1998). Genetic Heterogeneity of Annular epidermolytic ichthyosis AEI2 (620148) is caused by mutation in the KRT1 gene (139350) on chromosome 12q13. [from OMIM]

Ichthyosis with confetti (IWC), also known as congenital reticular ichthyosiform erythroderma (CRIE), is a rare skin condition characterized by slowly enlarging islands of normal skin surrounded by erythematous ichthyotic patches in a reticulated pattern. The condition starts in infancy as a lamellar ichthyosis, with small islands of normal skin resembling confetti appearing in late childhood and at puberty. Histopathologic findings include band-like parakeratosis, psoriasiform acanthosis, and vacuolization of keratinocytes with binucleated cells in the upper epidermis, sometimes associated with amyloid deposition in the dermis. Ultrastructural abnormalities include perinuclear shells formed from a network of fine filaments in the upper epidermis (summary by Krunic et al., 2003). [from OMIM]

The Lambert type of ichthyosis hystrix (IHL) is characterized by normal skin at birth that develops striking spiny hyperkeratotic lesions within a few months. There is sparing of the face, palms, and soles, and affected individuals do not experience blistering. Marked improvement of lesions during the summer months has also been observed in some patients. Ultrastructurally, binuclear cells and tonofilament shells surrounding the nucleus in upper keratinocytes are observed (summary by Penrose and Stern, 1958; Wang et al., 2007; Wang et al., 2016). Another form of ichthyosis hystrix, the Curth-Macklin type (IHCM; 146590), includes severe palmoplantar keratoderma among its features and is caused by mutation in the KRT1 (139350) gene. [from OMIM]