Patient present with skin bullae on sun exposure. There is a defect in which of the following?

Xeroderma pigmentosum Autosomal recessive disorder Defective DNA repair. Increased risk for skin cancers following exposure to the UV light UV radiation- Cross-linking of pyrimidine residues,-Preventing normal DNA replication. Such DNA damage is repaired by the nucleotide excision repair system. Deficiency of UV specific endonuclease (commonest), DNA polymerase and DNA ligase