This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genetics And Genetic Disorders, Subject name: Pediatrics
[{'content': "One of the parents who have a child with Down syndrome, has a balanced translocation between chromosome 15 and 21. What advice will you provide to the couple to prevent a child being born with Down syndrome? \nSelect and explain. \nA. Prenatal diagnosis and advice abortion, B. Artificial insemination with donor's sperm, C. Adoption, D. Does not matter", 'role': 'user'}, {'content': "Answer: A \nExplanation: a. Prenatal diagnosis and advice abortion(Ref: Nelson's 20/e p 610-615)Taking into view the chances of baby affected with Downs syndrome, prenatal diagnosis is advocated and abortion advised, if fetus is affected.Recurrence risk of Down syndrome, when a couple already has a child with Down syndrome depends on the karyotype of the affected child & his parents:Karyotype of affected childKaryotype of parentsRecurrence riskFatherMotherTrisomy 21NN 1%Translocation 21q21qNN 1%Either parent carrierQ100%NN 1%Translocationother chr with chr 21carrierN1-3%Ncarrier10-15%", 'role': 'assistant'}]