xeroderma pigmentosum

 
Pronunciation: /ˌpɪgmɛnˈtəʊsəm/

noun

[mass noun]
  • a rare hereditary defect of the enzyme system that repairs DNA after damage from ultraviolet rays, resulting in extreme sensitivity to sunlight and a tendency to develop skin cancer.

Origin:

late 19th century: pigmentosum, neuter of Latin pigmentosus 'pigmented'