Which of the following is true about xeroderma pigmentosa?

Ans. is 'd' i.e., DNA repair defect Xeroderma pigmentosaA. Molecular defect: - Exposure to UV rays damages DNA due to production of convalent linkages between adjacent pyrimidines (pyrimidine dimmers). Normally the damaged DNA is repaired by excision and repair. In xeroderma pigmentosa the repair of UV damaged DNA is defective. It is an autosomal recessive disorder.B. Clinical features: - Photosensitivity, multiple freckles, hypopigmented macules, xeroderma. There is increased risk of skin malignancy (Basal cell carcinoma, Squamous cell carcinoma, malignant melanoma). Most patients die before the age of 20 years (Premature death).