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DNA repair-deficient diseases, xeroderma pigmentosum, Cockayne syndrome and trichothiodystrophy

journal contribution
posted on 2023-06-08, 04:55 authored by Alan LehmannAlan Lehmann
Xeroderma pigmentosum (XP), Cockayne syndrome (CS) and trichothiodystrophy (TTD) are genetic disorders with very different clinical features, but all associated with defects in nucleotide excision repair. Defects in the XPA or XPC genes confer sensitivity to UV carcinogenesis in both humans and mice, but only XPA¿/¿ mice have increased acute responses to UV exposure, whereas XPC¿/¿ mice are normal in this respect. Both XPE and XPF proteins have functions separate from their role in NER, but the exact nature of these functions has not yet been established. The CSA and CSB genes responsible for CS are both components of complexes associated with RNA polymerase II and their role is thought to be in assisting polII in dealing with transcription blocks. XPB and XPD proteins are components of transcription factor TFIIH, which is involved in both basal and activated transcription. XPB is part of the core of TFIIH and has a central role in transcription, whereas XPD connects the core to the CAK subcomplex, and can tolerate many different mutations. Subtle differences in the effects of these different mutations on the many activities of TFIIH and on its stability determine the clinical outcomes, which can be XP, TTD, XP with CS, XP with TTD or COFS. Features of single and double mutant mice indicate that the neurological and ageing features associated with these disorders result from the defects in NER in association with the transcriptional deficiencies. Skin tumours in XP patients have mutations characteristic of UV-induction in the ras, p53 and ptch genes, showing that sunlight-induced mutations in these genes are important in carcinogenesis in XP patients.

History

Publication status

  • Published

Journal

Biochimie

ISSN

0300-9084

Publisher

Elsevier

Issue

11

Volume

85

Page range

1101-1111

Pages

11.0

Department affiliated with

  • Sussex Centre for Genome Damage Stability Publications

Full text available

  • No

Peer reviewed?

  • Yes

Legacy Posted Date

2012-02-06

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