Nucleotide excision repair diseases: molecular biology underlying the clinical heterogeneity

Xeroderma pigmentosum is a rare autosomal recessive disorder that occurs because of a defect in nucleotide excision repair (NER), an important DNA repair pathway involving in the removal of a wide array of direct and indirect DNA lesions. The absence or dysfunction of NER results in three distinct disorders (i.e. xeroderma pigmentosum, Cockayne syndrome, and trichothiodystrophy) associated with different clinical symptoms. Considering this clinical heterogeneity, it can be debated whether all clinical symptoms are related to the defect in the NER pathway or whether NER factors can participate in other biological processes. In this review, we discuss the effects of NER factors in oxidative and energy metabolism as a potential explanation for the clinical heterogeneity observed among different NER patients.