<prompt> Which of the following is a marker for Downs Syndrome?Increased maternal estriaolDecresed maternal serum alpha feto proteinDecreased HCGIncreased CA-125  <response>: Ans. is b i.e., Decresed maternal serum alpha feto protein Antenatal Screening for Downs syndromeo Following methods are used :-1 Triple test: It includesi Unconjugated estrogen estriol: decreased;ii Maternal serum alpha- feto protein MSAFP: decreased; andiii hCG: increasedNote: All these three markers are decreased in Edward syndrome2 New markers: These are i Increased inhibin A in maternal blood; and ii Decreased PAPA pregnancy associated plasma protein.3 USG: It shows: i Increased nuchal translucency increased nuchal fold thickness in first trimester; ii Ductus venous flow reversed; and iii Nasal bone hypoplasia.4 Karyotyping: It can be done by chorionic villus sampling at 10-12 weeks or aminocentesis at 16-18 weeks. 