Our cases confirm the severe phenotype associated with the p.Arg722Trp mutation and expand the known genetic mutations associated with trichothiodystrophy by demonstrating a novel pathogenic mutation in ERCC2.
Patient TTD24PV was compound heterozygous for a typical TTD allele (c.2164C>T</span>, p.Arg722Trp) and for a new XPD allele with a mutation that partially affects intron 10 splicing, resulting in both mutated and normal XPD transcripts (that together represent 15% of the total XPD mRNA).
Mutations of Arg658 to either His or Cys correlate with TTD cell strains with intermediate UV-sensitivity, mutation of Arg722 to Trp correlates with highly UV-sensitive TTD cell strains, and mutation of Arg683 to Trp correlates with XP-D. Alleles with mutation of Arg616 to Pro or with the combined mutation of Leu461 to Val and deletion of 716-730 are found in both XP-D and TTD cell strains.