Porokeratosis is a rare skin disorder characterized by one or more annular plaques with a surrounding raised horny border that spreads centrifugally. Variants of porokeratosis have been described that differ in morphologic shapes, distribution, and clinical course (Schamroth et al., 1997). However, as noted by Sybert (2010), families with expression of more than one variant of porokeratosis among members, and individuals expressing more than one variant, have been reported, suggesting that the distinctions among these variants may be artificial. Porokeratosis palmaris plantaris et disseminata (PPPD) is a subtype in which lesions initially develop on the palms and soles, but later involve other parts of the body, including the trunk and limbs (Wei et al., 2003). For a discussion of genetic heterogeneity of porokeratosis, see 174800.

Porokeratosis is a rare skin disorder characterized by one or more annular plaques with a surrounding raised horny border that spreads centrifugally. Variants of porokeratosis have been described that differ in morphologic shapes, distribution, and clinical course (Schamroth et al., 1997). However, as noted by Sybert (2010), several families with expression of more than one variant of porokeratosis among members, and several individuals expressing more than one variant, have been reported, suggesting that the distinctions among these variants may be artificial. Mutations in the MVK gene have been found to cause multiple types of porokeratosis, which have been described as porokeratosis of Mibelli, porokeratoma, genital porokeratosis, hyperkeratotic porokeratosis, and linear porokeratosis. The preferred title of this entry was formerly 'Porokeratosis 1, Mibelli Type; POROK1.' Genetic Heterogeneity of Porokeratosis Also see porokeratosis-2 (POROK2; 175850), mapped to chromosome 12q24; POROK3 (175900), caused by mutation in the MVK gene (251170) on chromosome 12q24; POROK4 (607728), mapped to chromosome 15q25-q26; POROK5 (612293), mapped to chromosome 1p31; POROK6 (612353), mapped to chromosome 1p31; POROK7 (614714), caused by mutation in the MVD gene (603236) on chromosome 16q24; POROK8 (616063), caused by mutation in the SLC17A9 gene (612107) on chromosome 20q13; and POROK9 (616631), caused by mutation in the FDPS gene (134629) on chromosome 1q22. A palmoplantar form of punctate porokeratosis has also been described (PPKP2; 175860). Genotype/Phenotype Correlations Zhang et al. (2015) screened 12 isoprenoid genes in 134 Chinese probands with porokeratosis and identified mutations in the MVK, MVD, PMVK, and FDPS genes in 113 patients. The authors noted that giant plaque-type porokeratosis ptychotropica with lesion diameters of at least 5 cm appeared to be uniquely associated with mutation in MVK; it was observed in 19 (50%) of 38 MVK probands, but not in patients with mutations in any of the other 3 genes or in the 21 probands in whom no mutation was found. MVK patients also showed the widest range in terms of the number and size of lesions, as well as presence of porokeratosis subtypes. In patients with MVD mutations, the age of onset ranged from 5 to 70 years, and lesion diameters were generally less than 2 cm. In addition, 6 of the 62 MVD probands exhibited solar facial porokeratosis, which was not seen in any other patients. Localized genital porokeratosis and porokeratoma appeared to be uniquely associated with mutation in the PMVK gene, whereas patients with mutations in the FDPS gene had more than 500 lesions, all with diameters of 1 cm or less.

CDAGS syndrome is characterized by craniosynostosis and clavicular hypoplasia, delayed closure of the fontanel, anal and genitourinary anomalies, and skin eruption of porokeratotic lesions (Mendoza-Londono et al., 2005).

Porokeratosis is a rare skin disorder characterized by one or more annular plaques with a surrounding raised horny border that spreads centrifugally. Variants of porokeratosis have been described that differ in morphologic shapes, distribution, and clinical course (Schamroth et al., 1997). However, as noted by Sybert (2010), several families with expression of more than one variant of porokeratosis among members, and individuals expressing more than one variant, have been reported, suggesting that the distinctions among these variants may be artificial. Mutations in the MVK gene have been found to cause multiple types of porokeratosis, which have been described as disseminated superficial actinic porokeratosis (DSAP), nonactinic disseminated superficial porokeratosis (DSP), porokeratosis of Mibelli, giant plaque of porokeratosis ptychotropica, hyperkeratotic porokeratosis, and linear porokeratosis. The preferred title of this entry was formerly 'Porokeratosis 3, Disseminated Superficial Actinic Type; POROK3.' Disseminated superficial actinic porokeratosis is the most common subtype of porokeratosis. It is characterized by multiple small, annular, anhidrotic, keratotic lesions that are located predominantly on sun-exposed areas of the skin, such as the face, neck, and distal limbs. The lesions typically begin to develop in adolescence and reach near-complete penetrance by the third or fourth decade of life (summary by Wu et al., 2004 and Zhang et al., 2012). For a discussion of genetic heterogeneity of porokeratosis, see 175800.

A type of isolated punctate hereditary palmoplantar keratoderma with characteristics of multiple asymptomatic 1 to 2 mm-long, firm, hyperkeratotic projections (spiny keratosis) on the palms, soles and digits (typically confined to their volar and/or lateral aspects). Histopathologically compact columnar parakeratosis over hypo or agranular epidermis is observed.

Porokeratosis is a rare skin disorder characterized by one or more annular plaques with a surrounding raised horny border that spreads centrifugally. Variants of porokeratosis have been described that differ in morphologic shapes, distribution, and clinical course (Schamroth et al., 1997). However, as noted by Sybert (2010), reports of several families with expression of more than one variant of porokeratosis among members, and of individuals expressing more than one variant, suggest that the distinctions among these variants may be artificial. Disseminated superficial actinic porokeratosis (DSAP) is the most common subtype of porokeratosis. It is characterized by multiple small, annular, anhidrotic, keratotic lesions that are located predominantly on sun-exposed areas of the skin, such as the face, neck, and distal limbs. The lesions typically begin to develop in adolescence and reach near-complete penetrance by the third or fourth decade of life (summary by Wu et al., 2004 and Zhang et al., 2012).

Porokeratosis is a rare skin disorder characterized by one or more annular plaques with a surrounding raised horny border that spreads centrifugally. Variants of porokeratosis have been described that differ in morphologic shapes, distribution, and clinical course (Schamroth et al., 1997). However, as noted by Sybert (2010), several families with expression of more than one variant of porokeratosis among members, and individuals expressing more than one variant, have been reported, suggesting that the distinctions among these variants may be artificial. Mutations in the MVD gene have been found to cause multiple types of porokeratosis, which have been described as disseminated superficial actinic porokeratosis (DSAP), nonactinic disseminated superficial porokeratosis (DSP), solar facial porokeratosis, linear porokeratosis, and hyperkeratotic porokeratosis. The preferred title of this entry was formerly 'Porokeratosis 7, Disseminated Superficial Actinic Type; POROK7.' Disseminated superficial actinic porokeratosis (DSAP) is the most common subtype of porokeratosis. It is characterized by multiple small, annular, anhidrotic, keratotic lesions that are located predominantly on sun-exposed areas of the skin, such as the face, neck, and distal limbs. The lesions typically begin to develop in adolescence and reach near-complete penetrance by the third or fourth decade of life (summary by Wu et al., 2004 and Zhang et al., 2012). For a discussion of genetic heterogeneity of porokeratosis, see 175800.

Porokeratosis is a rare skin disorder characterized by one or more annular plaques with a surrounding raised horny border that spreads centrifugally. Variants of porokeratosis have been described that differ in morphologic shape, distribution, and clinical course (Schamroth et al., 1997). However, as noted by Sybert (2010), the existence of several families with expression of more than one variant of porokeratosis among members, and individuals expressing more than one variant, suggest that the distinctions among these variants may be artificial. Disseminated superficial actinic porokeratosis (DSAP) is the most common subtype of porokeratosis. It is characterized by multiple small, annular, anhidrotic, keratotic lesions that are located predominantly on sun-exposed areas of the skin, such as the face, neck, and distal limbs. The lesions typically begin to develop in adolescence and reach near-complete penetrance by the third or fourth decade of life (summary by Wu et al., 2004 and Zhang et al., 2012). For a discussion of genetic heterogeneity of porokeratosis, see 175800.

Porokeratosis is a rare skin disorder characterized by one or more annular plaques with a surrounding raised horny border that spreads centrifugally. Variants of porokeratosis have been described that differ in morphologic shapes, distribution, and clinical course (Schamroth et al., 1997). However, as noted by Sybert (2010), several families with expression of more than one variant of porokeratosis among members, and individuals expressing more than one variant, have been reported, suggesting that the distinctions among these variants may be artificial. Mutations in the FDPS gene have been found to cause multiple types of porokeratosis, which have been described as disseminated superficial actinic porokeratosis (DSAP) and nonactinic disseminated superficial porokeratosis (DSP). For a discussion of genetic heterogeneity of porokeratosis, see 174800.