Reinvestigation of the classification of five cell strains of xeroderma pigmentosum group E with reclassification of three of them

J Invest Dermatol. 2000 May;114(5):1022-9. doi: 10.1046/j.1523-1747.2000.00952.x.


Xeroderma pigmentosum is a photosensitive syndrome caused by a defect in nucleotide excision repair or postreplication repair. Individuals of xeroderma pigmentosum group E (xeroderma pigmentosum E) have a mild clinical form of the disease and their cells exhibit a high level of nucleotide excision repair as measured by unscheduled DNA synthesis, as well as biochemical heterogeneity. Cell strains from one group of xeroderma pigmentosum E patients have normal damage-specific DNA binding activity (Ddb+), whereas others do not (Ddb-). Using a refinement of a previously reported cell fusion complementation assay, the previously assigned Ddb+ xeroderma pigmentosum E strains, XP89TO, XP43TO, and XP24KO, with various phenotypes in DNA repair markers, were reassigned to xeroderma pigmentosum group F, xeroderma pigmentosum variant, and ultraviolet-sensitive syndrome, respectively. The Ddb- xeroderma pigmentosum E strains, XP82TO, and GM02415B, which showed almost normal cellular phenotypes in DNA repair markers, however, remained assigned to xeroderma pigmentosum group E. With the exception of the Ddb+ strain XP89TO, which demonstrated defective nucleotide excision repair, both Ddb- and Ddb+ xeroderma pigmentosum E cells exhibited the same levels of variation in unscheduled DNA synthesis that were seen in normal control cells. By genome DNA sequencing, the two Ddb- xeroderma pigmentosum E strains were shown to have mutations in the DDB2 gene, confirming previous reports for XP82TO and GM02415B, and validating the classification of both cells. As only the Ddb- strains investigated remain classified in the xeroderma pigmentosum E complementation group, it is feasible that only Ddb- cells are xeroderma pigmentosum E and that mutations in the DDB2 gene are solely responsible for the xeroderma pigmentosum E group.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • DNA / biosynthesis
  • DNA Repair
  • DNA-Binding Proteins / genetics
  • Humans
  • Mutation
  • Radiation Tolerance
  • Ultraviolet Rays
  • Xeroderma Pigmentosum / pathology*


  • DDB2 protein, human
  • DNA-Binding Proteins
  • DNA