Xeroderma pigmentosum is caused due to:
Xeroderma pigmentosum (XP) is a rare autosomal recessive disease characterized by photosensitivity, pigmentary changes, premature skin ageing, neoplasia and abnormal Nucleotide excision repair. Ref: Rook's textbook of dermatology, 8th edition, Pg15.71.
DNA synthesis defect
Ectodermal cell migration defect
Abnormal nucleotide excision repair
Melanocyte proliferation