title: A novel mutation in the keratin 4 gene causing white sponge naevus.
abstract: BACKGROUND
  White sponge naevus (WSN) is a rare, autosomal dominant disorder that predominantly affects noncornified stratified squamous epithelia, most commonly the buccal mucosa. Clinically, WSN manifests as thickened spongy mucosa with a white opalescent tint in the mouth and may be confused with other disorders that cause white lesions on oral mucosa. Recent studies have identified pathogenic mutations in KRT4 and KRT13, the genes encoding mucosa-specific keratins, in WSN.
  
  
  OBJECTIVE
  To search for possible mutations in KRT4 and KRT13.
  
  
  METHODS
  We report a case of WSN in a young man who presented with diffuse irregular whitish plaques involving the buccal and gingival mucosae and the tongue. Results Pathologically, the affected mucosa showed epithelial thickening, parakeratosis and extensive vacuolization of the suprabasal keratinocytes. Mutation analysis revealed a heterozygous missense mutation 1345G-->A in KRT4, predicting an amino acid change, E449K, in the 2B domain of the K4 polypeptide.
  
  
  CONCLUSIONS
  We report the first mutation analysis of a Taiwanese patient with WSN. Potentially this novel mutation could disrupt the stability of keratin filaments and result in WSN.
authors.affiliation: Department of Dermatology, National Cheng-Kung University Hospital, 138 Sheng-Li Road, Tainan, Taiwan.
authors.forename: S-C
authors.initials: SC
authors.lastname: Chao
authors.forename: Y-M
authors.initials: YM
authors.lastname: Tsai
authors.forename: M-H
authors.initials: MH
authors.lastname: Yang
authors.forename: J Y-Y
authors.initials: JY
authors.lastname: Lee
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D001483:Base Sequence; D006801:Humans; D007633:Keratins / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D009061:Mouth Mucosa; D009062:Mouth Neoplasms / Q000235:genetics*; D009154:Mutation / Q000235:genetics*; D009506:Nevus / Q000235:genetics*; D010375:Pedigree; D016133:Polymerase Chain Reaction / Q000379:methods; D012878:Skin Neoplasms / Q000235:genetics*
chemical_list: D007633:Keratins