| • | AKA Mutilating Keratoderma of Vohwinkel |
| • | pathogenesis: mutation in loricrin |
| • | palmoplantar hyperkeratosis of the honeycomb type |
| • | starfishlike and linear keratoses of the backs of the hands, elbows, and knees |
| • | annular constriction (pseudo-ainhum) of the digits; which may progress to autoamputation |
| • | treatment: hyperkeratosis and the pseudo-ainhum respond to acitretin |
| • | the corneocyte has a highly insoluble cornified envelope its formation represents an expression of terminal differentiation of the keratinocyte within the plasma membrane, formed by the cross-linking of the soluble protein precursor involucrin (Greek = envelope) |
| • | envelope precursors (e.g. involucrin, loricrin) are synthesized late in stratification and then cross-linked by the action of transglutaminase enzymes, which are synthesized in the granular layer |
| • | major cell envelope constituents = involucrin, filaggrin and loricrin |
| • | defect in ichthyosis vulgaris – filaggrin |
| • | defect in Vohlwinkel’s syndrome – loricrin |
| • | defect in lamellar ichthyosis - transglutaminase |
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