This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
[{'content': 'What known chromosomal reason could explain for autosomal recessive disorders where one parent is unaffected and the other is a carrier to cause the condition for the child? \nSelect and explain. \nA. Germ line mosaicism, B. Genomic imprinting, C. Penetration, D. Uniparental disomy', 'role': 'user'}, {'content': "Answer: D \nExplanation: An interesting corollary of uniparental disomy is that it can result in a child being affected by an autosomal recessive disorder when only one parent is a carrier for that disorder. The son or the daughter inherits two identical copies of the chromosome with the mutation (isodisomy) and so develops the disease. Uniparental disomy (UPD) occurs when a person receives two copies of a chromosome, or pa of a chromosome, from one parent and no copies from the other parent. Ref: Mosby's Medical Dictionary, 8th edition. (c) 2009, Elsevier; Nelson's Textbook of Paediatrics 17th Edition, Page 389; Metabolic Encephalopathies: Therapy and Prognosis By Stefano Di Donato, 1995, Page 198.", 'role': 'assistant'}]