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: Pathology
[{'content': "What percentage of Down's syndrome patients also have congenital cardiovascular disease? \nSelect and explain. \nA. 0.10%, B. 3%, C. 20%, D. 50%", 'role': 'user'}, {'content': "Answer: C \nExplanation: This fact is woh remembering: one-fifth of Down's syndrome patients have congenital cardiovascular disease, most commonly an ostium primum type of ASD and/or a ventricular septal defect. This is a sufficiently high incidence to justify at least one echocardiogram in each of these children's lives. Affected children are also paicularly vulnerable to seizures, and as adults may develop an Alzheimer-like dementia in their mid 40s. Ref: Wyatt C., Kemp W.L., Moos P.J., Burns D.K., Brown T.G. (2008). Chapter 6. Genetic Disorders. In C. Wyatt, W.L. Kemp, P.J. Moos, D.K. Burns, T.G. Brown (Eds), Pathology: The Big Picture.", 'role': 'assistant'}]