Because most mutated XPC alleles in xeroderma pigmentosum families lead to premature terminations as a result of frameshifts, nonsense mutations, deletions, insertions or aberrant splicing, only one single substitution, which causes a Trp690Ser change, has been identified in the evolutionary conserved region of XPC protein [29]. The gene discussed is XPC; the disease is xeroderma pigmentosum.