The literature describes multiple individuals in whom these two ERCC2 variants occur in cis and as part of a complex allele of compound heterozygous genotypes with other pathogenic alleles and features of xeroderma pigmentosum (XPD; OMIM #278730) and trichothiodystrophy (TTD1; OMIM #601675) [25,26,27]. Here, ERCC2 is linked to xeroderma pigmentosum.