This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autoimmune skin disorders, Subject name: Dental
[{'content': 'Melanocytes are reduced in number in all of the following Except \nSelect and explain. \nA. Albinism, B. Vitiligo, C. Piebaldism, D. Chemical induced hypopigmentation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Albinism is a defect in the synthesis of melanin. Melanocytes are normally present and distributed Disorders of reduced melanin synthesis: albinism, Chediak-Higashi and Hermansky-Pudlack Reduced melanocytes is seen in vitiligo, piebaldism and Waardenburg syndrome Albinism. Albinism is a group of genetic disorders characterized by reduced or absent melanin pigmentation, with an overall estimated frequency of about 1 per 20000 in most populations (Ref: Harrison 20th edition pg 1234', 'role': 'assistant'}]