Nucleotide Excision Repair/Transcription Coupled Repair

Nucleotide excision is a DNA repair mechanism which removes nucleotides that have been damaged by chemicals or ultraviolet radiation. Nucleotide excision generates a short single-stranded DNA gap, which is subsequently used as a template by DNA polymerase. The importance of nucleotide excision repair is underlined by genetic mutations, which result in Xeroderma Pigmentosum (XP), an autosomal recessive disorder characterized by extreme sensitivity to ultraviolet light and a predisposition to skin cancer.