title: Linkage of an American pedigree with palmoplantar keratoderma and malignancy (palmoplantar ectodermal dysplasia type III) to 17q24. Literature survey and proposed updated classification of the keratodermas.
abstract: OBJECTIVE
  To determine linkage in a pedigree with palmoplantar keratoderma (PPK) associated with squamous cell carcinoma of the esophagus.
  
  
  METHODS
  A large American pedigree was studied and the clinical phenotype was described. Linkage analysis was performed using genomic DNA from key individuals.
  
  
  METHODS
  A community-based family study.
  
  
  METHODS
  The family pedigree was expanded from a single index case.
  
  
  METHODS
  To demonstrate linkage and the relative risk of squamous cell carcinoma of the esophagus in this pedigree.
  
  
  RESULTS
  Focal PPK was inherited as an autosomal dominant with variable expression, but signs were not limited to the palmoplantar epidermis. The generalized nature of this pattern of PPK was highlighted by the perifollicular papules and oral hyperkeratosis. Affected individuals (125 individuals) in 7 generations were identified, with 17 affected individuals having associated cancer. Seven of the 8 squamous cell carcinomas of the esophagus occurred in smokers. Other tumors were seen in nonsmokers, but these were not significantly increased. The combined male-female expected incidence of squamous cell carcinoma of the mouth and esophagus was 0.21; observed, 8 (relative risk of 38; P < .001). Linkage to the tylosis and esophageal cancer gene locus on 17q24 was demonstrated with a maximum 2-point lod score of 8.20 at zero recombination fraction for the DNA marker D17S1603.
  
  
  CONCLUSIONS
  The distinctive clinical phenotype in this family suggests a new classification for PPKs, in particular a reappraisal of the phenotype as a focal PPK. A very similar phenotype is found in patients with keratin K16 gene mutations.
authors.affiliation: Imperial Cancer Research Fund (ICRF) Skin Tumour Laboratory, London Hospital Medical College, England.
authors.forename: H P
authors.initials: HP
authors.lastname: Stevens
authors.forename: D P
authors.initials: DP
authors.lastname: Kelsell
authors.forename: S P
authors.initials: SP
authors.lastname: Bryant
authors.forename: D T
authors.initials: DT
authors.lastname: Bishop
authors.forename: N K
authors.initials: NK
authors.lastname: Spurr
authors.forename: J
authors.initials: J
authors.lastname: Weissenbach
authors.forename: D
authors.initials: D
authors.lastname: Marger
authors.forename: R S
authors.initials: RS
authors.lastname: Marger
authors.forename: I M
authors.initials: IM
authors.lastname: Leigh
mesh_terms: D002886:Chromosomes, Human, Pair 17; D004476:Ectodermal Dysplasia / Q000150:complications / Q000235:genetics*; D005260:Female; D008040:Genetic Linkage; D006801:Humans; D007645:Keratoderma, Palmoplantar / Q000145:classification / Q000150:complications / Q000235:genetics*; D008297:Male; D009369:Neoplasms / Q000150:complications / Q000235:genetics*; D010375:Pedigree; D010641:Phenotype; D014481:United States