Abbreviations: bp, base pair; CS, Cockayne syndrome; E [number], embryonic day [number]; kb,
kilobase; NER, nucleotide excision repair; SEM, standard error of the mean; TFIIH, basal transcription / DNA repair factor IIH; TTD, trichothiodystrophy; UV - RRS, recovery of
RNA synthesis after ultraviolet irradiation; UV - UDS, unscheduled DNA synthesis after ultraviolet irradiation; wt, wild - type; XP, xeroderma pigmentosum; XPCS, xeroderma pigmentosum combined with Cockayne syndrome; XPTTD, combination xeroderma pigmentosum and trichothiodystrophy