An inherited skin disorder characterized by photosensitivity with severe sunburn in infancy, the development of numerous pigmented spots resembling freckles, larger atrophic lesions associated with telangiectasis, and multiple solar keratoses. Transmitted in an autosomal recessive manner, xeroderma pigmentosa involves a defect in nucleotide excision repair (NER), leading to deficient repair of DNA damaged by UV radiation and chromosome breakage. Individuals with this disease develop multiple malignant cutaneous neoplasms at an early age and may suffer from severe ophthalmic and neurologic abnormalities.