Constructive rescue of TFIIH instability by an alternative isoform of XPD derived from a mutated XPD allele in mild but not severe XP-D/CS

J Hum Genet. 2015 May;60(5):259-65. doi: 10.1038/jhg.2015.18. Epub 2015 Feb 26.

Abstract

Mutations in XPD cause xeroderma pigmentosum (XP), XP and Cockayne syndrome (CS) crossover syndrome (XP/CS), trichothiodystrophy and cerebro-oculo-facio-skeletal syndrome (COFS). COFS represents the most severe end of the CS spectrum. This study reports two Japanese patients, COFS-05-135 and COFS-Chiba1, who died at ages of <1 year and exhibited typical COFS manifestations caused by XPD mutations p.[I619del];[R666W] and p.[G47R];[I619del], respectively. Two other cases of severe XP-D/CS (XP group D/CS), XP1JI (p.[G47R];[0]) and XPCS1PV (p.[R666W];[0]), died at ages <2 years. On the other hand, two cases of mild XP-D/CS, XP1NE (p.[G47R];[L461V;V716_R730del]) and XPCS118LV (p.[L461V;V716_R730del];[R666W]), lived beyond 37 years of age. p.I619Del and p.[L461V;V716_R730del] are functionally null; therefore, despite the differences in clinical manifestations, the functional protein in all of these patients was either p.G47R or p.R666W. To resolve the discrepancies in these XPD genotype-phenotype relationships, the p.[L461V;V716_R730del] allele was analyzed and we found that p.[L461V;A717G] was expressed from the same allele as p.[L461V;V716_R730del] by authentic splicing. Additionally, p.[L461V;A717G] could partially rescue the loss of XPD function, resulting in the milder manifestations observed in XP1NE and XPCS118LV.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Fatal Outcome
  • Female
  • Genetic Association Studies
  • Humans
  • Infant
  • Male
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • Protein Stability
  • Transcription Factor TFIIH / genetics*
  • Transcription Factor TFIIH / metabolism
  • Xeroderma Pigmentosum / genetics*
  • Xeroderma Pigmentosum Group D Protein / genetics*
  • Xeroderma Pigmentosum Group D Protein / metabolism

Substances

  • Protein Isoforms
  • Transcription Factor TFIIH
  • Xeroderma Pigmentosum Group D Protein
  • ERCC2 protein, human