ERCC2 and xeroderma pigmentosum-Cockayne syndrome complex: The xeroderma pigmentosum group D (XPD) gene, also known as ERCC2, encodes a 5′–3′ superfamily 2 helicase that plays a key role in unwinding the DNA double helix around damaged DNA during nucleotide excision repair (NER) (Kuper et al., 2012; Constantinescu-Aruxandei et al., 2016).