Darier-White disease (DAR), also known as keratosis follicularis, is an autosomal dominant skin disorder characterized by warty papules and plaques in seborrheic areas (central trunk, flexures, scalp, and forehead), palmoplantar pits, and distinctive nail abnormalities (Sakuntabhai et al., 1999). Onset is usually before the third decade, and penetrance is complete in adults, although expressivity is variable. Involvement may be severe, with widespread itchy malodorous crusted plaques, painful erosions, blistering, and mucosal lesions. Secondary infection is common. Sun, heat, and sweating exacerbate the symptoms. Darier disease never remits, but oral retinoids may reduce hyperkeratosis. Neuropsychiatric abnormalities, including mild mental retardation and epilepsy, have been described in association with Darier disease in a few families (Burge and Wilkinson, 1992); whether this is an association based on pleiotropism of the mutant gene or reflects coincidence is not clear. Histologic findings are (1) mild nonspecific perivascular infiltration in the dermis; (2) dermal villi protruding into the epidermis; (3) suprabasal detachment of the spinal layer leading to the formation of lacunae containing acantholytic cells; (4) in the more superficial epidermis, dyskeratotic round epidermal cells ('corps ronds'), the most distinctive feature; and (5) in the stratum corneum, 'grains' that resemble parakeratotic cells embedded in a hyperkeratotic horny layer. Electron microscopy reveals loss of desmosomal attachments, perinuclear aggregations of keratin filaments, and cytoplasmic vacuolization. Ultrastructural and immunologic studies suggest the disease results from an abnormality in the desmosome-keratin filament complex leading to a breakdown in cell adhesion.

Acrokeratosis verruciformis of Hopf (AKV) is a localized disorder of keratinization affecting the distal extremities. Onset occurs early in life (Dhitavat et al., 2003).

Naxos disease (NXD) is characterized by arrhythmogenic right ventricular cardiomyopathy associated with abnormalities of the skin, hair, and nails. The ectodermal features are evident from birth or early childhood, whereas the cardiac symptoms develop in young adulthood or later. Clinical variability of ectodermal features has been observed, with hair anomalies ranging from woolly hair to alopecia, and skin abnormalities ranging from mild focal palmoplantar keratoderma to generalized skin fragility or even lethal neonatal epidermolysis bullosa (Protonotarios et al., 1986; Cabral et al., 2010; Pigors et al., 2011; Erken et al., 2011; Sen-Chowdhry and McKenna, 2014). Another syndrome involving cardiomyopathy, woolly hair, and keratoderma (DCWHK; 605676) is caused by mutation in the desmoplakin gene (DSP; 125647). Also see 610476 for a similar disorder caused by homozygous mutation in the DSC2 gene (125645).

Woolly hair-skin fragility syndrome (WHSF) is characterized by woolly hair texture and slow hair growth, as well as superficial skin fragility which is present at birth or appears in the neonatal period and then resolves or persists only as minor palmoplantar skin peeling. The disorder appears to predominantly affect hair, and to a lesser extent skin (Jackson et al., 2023).

Dilated cardiomyopathy with woolly hair and keratoderma (DCWHK) is characterized by the presence of woolly or sparse hair from birth. Some patients exhibit fragile skin with blisters/erosions after minor mechanical trauma, with hyperkeratosis and epidermolytic keratoderma developing in early childhood. Cardiomyopathy may become apparent in the first decade of life, and early death due to heart failure has been reported, but patients may remain asymptomatic into the fourth decade of life. Some patients exhibit an arrhythmogenic form of cardiomyopathy, with sudden death in early adulthood (Carvajal-Huerta, 1998; Whittock et al., 2002; Alcalai et al., 2003; Uzumcu et al., 2006). Another syndrome involving cardiomyopathy, woolly hair, and keratoderma (Naxos disease; 601214) is caused by mutation in the plakoglobin gene (JUP; 173325). Also see 610476 for a similar disorder caused by homozygous mutation in the DSC2 gene (125645). Dilated cardiomyopathy with woolly hair, keratoderma, and tooth agenesis (DCWHKTA; 615821) is caused by heterozygous mutation in DSP. An isolated form of striated PPK (PPKS2; 612908) is also caused by heterozygous mutation in DSP. Reviews In a review of cardiocutaneous syndromes and arrhythmogenic cardiomyopathy, Sen-Chowdhry and McKenna (2014) stated that although the cardiac component of Carvajal syndrome was originally considered dilated cardiomyopathy, many of its features resemble those of arrhythmogenic cardiomyopathy (see 607450). In addition, they noted that different disease subtypes have been found to coexist within the same kindred, suggesting a role for modifier genes and/or environmental influences.

Lethal acantholytic epidermolysis bullosa (EBLA) is an autosomal recessive skin disorder characterized by extensive epidermal dislodgment, universal alopecia, and anonychia. Cardiac involvement may be present. Death occurs in the neonatal period (summary by Hobbs et al., 2010).

A rare genetic epidermal disorder with characteristics of congenital erythroderma with severe psoriasiform dermatitis, ichthyosis, severe palmoplantar keratoderma, yellow keratosis on the hands and feet, elevated immunoglobulin E, multiple food allergies, and metabolic wasting. Other variable features may include hypotrichosis, nail dystrophy, recurrent infections, mild global developmental delay, eosinophilia, nystagmus, growth impairment and cardiac defects.

A rare genetic skin disease characterized by generalized skin peeling, leukonychia, acral punctate keratoses coalescing into focal keratoderma on the weight-bearing areas, angular cheilitis and knuckle pads with multiple hyperkeratotic micropapules. The skin appears dry and scaly with superficial exfoliation and underlying erythema. Histopathologic examination of affected skin areas shows hyperkeratosis, acanthosis and intraepidermal clefting with irregular acantholysis. Additional systemic abnormalities are absent.