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
In the first trimester screening for Down syndrome which of the following test is to be done? 
Select and explain. 
A. Beta HCG, PAPPA, B. MSAFP, PAPPA, C. Inhibin, PAPPA, D. Unconjugated Estriol, PAPPAs
A: Beta HCG, PAPPA
Answer: A: Beta HCG, PAPPA 
Explanation: a. Beta HCG, PAPPA(Ref: Nelson's 20/e p 610-615)Methods for Antenatal Screening for Down Syndrome - In 1st Trimester pg 79Screening methodDetection rateMaternal age + Biochemical markers (b-hCG, PAPPA)Q70%Maternal age + Radiology (USG- NT>3mm)80%-83%Combined test: Mat. Age + Radiology (USG-NT>3mm)82%-87%*PAPPA is Pregnancy Associated Plasma Protein A