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Analysis of the KRT9 Gene in a Mexican Family with Epidermolytic Palmoplantar Keratoderma

Authors

  • Jaime Lopez-Valdez M.D.,

    1. Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, México City, DF, México
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  • Maria Refugio Rivera-Vega M.D.,

    1. Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, México City, DF, México
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  • Luz Maria Gonzalez-Huerta M.D.,

    1. Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, México City, DF, México
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  • Jorge Cazarin M.D.,

    1. Servicio de Dermatología, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, México City, DF, México
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  • Sergio Cuevas-Covarrubias Ph.D.

    Corresponding author
    • Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, México City, DF, México
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Address correspondence to Sergio Cuevas-Covarrubias, Ph.D., Servicio de Genética, Hospital General de México, Facultad de Medicina, UNAM, Dr. Balmis 148, Col. Doctores, C.P. 06726, México DF, México, or e-mail: sercuevas@yahoo.com.

Abstract

Epidermolytic palmoplantar keratoderma (EPPK), an autosomal-dominant genodermatosis, is the most frequently occurring hereditary palmoplantar keratoderma. EPPK is characterized by hyperkeratosis of the palms and soles. Approximately 90% of patients present with mutations in the KRT9 gene, which encodes for keratin 9. Many of these mutations are located within the highly conserved coil 1A region of the alpha-helical rod domain of keratin 9, an important domain for keratin heterodimerization. The objective was to assess the clinical and molecular characteristics of a Mexican family with EPPK. The clinical characteristics of members of this family were analyzed. The KRT9 gene of affected members was polymerase chain reaction amplified from genomic DNA and sequenced. All affected members of the family had hyperkeratosis of the palms and soles with knuckle pads. The R163W mutation in the KRT9 gene was present in all affected individuals who were tested. Although R163W is the most frequent KRT9 mutation in patients with EPPK, only two families have been reported with knuckle pads associated with this mutation. Our findings indicate that knuckle pads can be associated with EPPK and the R163W mutation in a family with a genetic background different from that described here.

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