Keratin 17 Mutations in Four Families from India with Pachyonychia Congenita.
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ABSTRACT:
SUBMITTER: Agarwala M
PROVIDER: S-EPMC5527726 | biostudies-other | 2017 Jul-Aug
REPOSITORIES: biostudies-other
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Project description:Keratins are heteropolymeric proteins that form the intermediate filament cytoskeleton in epithelial cells. The common basic structure of all keratins is organized in a central ?-helical rod domain flanked by nonhelical, variable head and tail regions. Most mutations in keratins are found in the central ?-helical rod domain. Keratin 9 (K9) is expressed only in the suprabasal layers of palmoplantar epidermis. Mutations in the keratin 9 gene (KRT9) have been shown to cause epidermolytic palmoplantar keratoderma (EPPK; OMIM 144200), an autosomal dominant genodermatosis characterized clinically by diffuse hyperkeratosis limited to the palms and soles, and histologically by epidermolysis in suprabasal layers of the epidermis.To elucidate the genetic basis of EPPK in five Pakistani families.Using microsatellite markers localized to the areas around the type I keratin gene cluster on chromosome 17q21, genotyping of these families was performed, followed by sequencing of the KRT9 gene.The analysis resulted in the identification of two novel (p.M157K and p.Y454H) and two recurrent (p.M157T and p.R163Q) mutations in the KRT9 of all five families. All mutations occurred within the highly conserved helix initiation or termination motif of K9.The affected members of all five families possess mutations in the KRT9 gene that severely affect heterodimer formation with the type II keratin partner. The results of our study further underscore the crucial role of K9 protein in the palmoplantar epidermis.
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Project description:This article describes the inter- and intra-familial phenotypic variability in four families with WNT10A mutations. Clinical characteristics of the patients range from mild to severe isolated tooth agenesis, over mild symptoms of ectodermal dysplasia, to more severe syndromic forms like odonto-onycho-dermal dysplasia (OODD) and Schöpf-Schulz-Passarge syndrome (SSPS). Recurrent WNT10A mutations were identified in all affected family members and the associated symptoms are presented with emphasis on the dentofacial phenotypes obtained with inter alia three-dimensional facial stereophotogrammetry. A comprehensive overview of the literature regarding WNT10A mutations, associated conditions and developmental defects is presented. We conclude that OODD and SSPS should be considered as variable expressions of the same WNT10A genotype. In all affected individuals, a dished-in facial appearance was observed which might be helpful in the clinical setting as a clue to the underlying genetic etiology.
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