<prompt> Cause of the xeroderma pigmentosum is?Missense mutationDNA rapair defectTrisomyProduction of guanine guanine dimmers in DNA  <response>: Ans. is b i.e. DNA repair defect Xeroderma pigmentosum is an autosomal recessive disease with defect in DNA repair. It is characterized by extreme sensitivity to sunlight. The enzymes affected in this condition are:1. UV specific endonuclease most common2. DNA polymerase I3. DNA ligase 