This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genetic and genetic disorders, Subject name: Pediatrics
Prenetal diagnosis of Down Syndrome is by 
Select and explain. 
A. Karyotyping, B. Triple test, C. Fetal ultrasonography, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Prenatal diagnosis of down syndrome can be done by all the above. Fetal ultrasonography or nuchal translucency scan is done in the first trimester. Triple test using alpha fetoprotein,unconjugated estriol and beta hCG helps in 2nd trimester also helps to detect down syndrome. Karyotyping helps to locate 3 copies of chromosome 21. Reference: Nelson TB of pediatrics 19th edition, pg 402