albinism vs vitiligo

albinism

noun
  • Congenital lack of melanin pigmentation in the skin, eyes, and hair or feathers (or more rarely only in the eyes); the condition of being albino. 

vitiligo

noun
  • The patchy loss of skin pigmentation. 

How often have the words albinism and vitiligo occurred in a corpus of books? (source: Google Ngram Viewer )