<prompt> Antenatal diagnosis of all of these disorders is possible except:Downs syndromeNoonans syndromeAnencephalySevere combined immunodeficiency syndrome  <response>: Ans. D. Severe combined immunodeficiency syndrome There are various methods for antenatal detection of different congenital disorders. Antenatal ultrasound is one of them. A first-trimester sonography can be used for confirming gestational age, singleton or multiple pregnancy and to measure nuchal thickness. Second-trimester sonography detects fetal structural defects. Nuchal translucency is a powerful tool to detect aneuploidy such as Downs syndrome; it is also increased in patients with Noonans syndrome, Stickler syndrome, and Miller-Dieker syndrome, among others. Anencephaly is a NTD that can also be detected prenatally with sonography and maternal serum alpha-fetoprotein MSAFP screening test. Prenatal genetic testing is not routinely done for severe combined immunodeficiency but is only available if a genetic cause has already been identified in the family. If a genetic cause has been identified, DNA from the fetus can be removed and tested. 