An abnormality of the skeletal system.

Slightly elevated lesions on or in the skin with a diameter of over 5 mm.

Classic Vohwinkel syndrome is characterized by papular and honeycomb keratoderma associated with constrictions of digits leading to autoamputation, distinctive starfish-like acral keratoses, and moderate degrees of sensorineural deafness (summary by Maestrini et al., 1999) A variant form of Vohwinkel syndrome, mutilating keratoderma with ichthyosis (604117), is caused by mutation in the gene for loricrin (LOR; 152445) on chromosome 1q21. A form of mutilating palmoplantar keratoderma with periorificial keratotic plaques (Olmsted syndrome; 614594) is caused by mutation in the TRPV3 gene (607066) on chromosome 17p13.2.

Bart-Pumphrey syndrome (BAPS) is an autosomal dominant disorder characterized by sensorineural hearing loss, palmoplantar keratoderma, knuckle pads, and leukonychia, which shows considerable phenotypic variability (summary by Richard et al., 2004).

Complete congenital absence of dermatoglyphs is a rare syndrome characterized by autosomal dominant inheritance of the lack of ridges on palms and soles, neonatal acral blisters and facial milia, adult traumatic blistering and fissuring, absent or reduced sweating of palms and soles, and contracture of digits. Additional features may include single palmar transverse crease, palmoplantar keratoderma, and nail grooving (summary by Limova et al., 1993).

The Curth-Macklin type of ichthyosis hystrix (IHCM) is clinically characterized by severe fissuring and mutilating palmoplantar keratoderma. Affected individuals also exhibit extensive dark spiky or verrucous hyperkeratotic plaques over the large joints and trunk, which in some patients may cover almost the entire body. Structural and ultrastructural hallmarks include compact orthokeratotic hyperkeratosis, hypergranulosis with perinuclear edema, binucleated cells, and formation of perinuclear filamentous shells composed of feathery entangled keratin intermediate filaments (summary by Richardson et al., 2006 and Fonseca et al., 2013). The Lambert type of ichthyosis hystrix (IHL; 146600), in which palms and soles are spared, is caused by mutation in the KRT10 (148080) gene.

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.

Some ectodermal dysplasias are here classified as congenital disorders characterized by abnormal development in 2 or more ectodermal structures (hair, nails, teeth, and sweat glands) without other systemic findings. Hypohidrotic, or anhidrotic, ectodermal dysplasia (HED/EDA) is characterized by a triad of signs comprising sparse hair (hypotrichosis), abnormal or missing teeth (anodontia or hypodontia), and inability to sweat (anhidrosis or hypohidrosis). Typical clinical manifestations also include dryness of the skin, eyes, airways, and mucous membranes presumably due to the defective development of several exocrine glands. Hypohidrotic ectodermal dysplasia can be associated with dysmorphic features (forehead bumps, rings under the eyes, everted nose, and prominent lips) and occasionally with absent nipples (summary by Cluzeau et al., 2011).