<prompt> All of the following are features of downs syndrome, EXCEPT:Increased PAPP-AIncreased free beta HCG levelsAbsent nasal boneAbnormal ductus venosus flow velocity  <response>: In Downs syndrome the level of AFP is low, PAAP-A is low, and B hCG is high. Characteristic features of Downs syndrome are: Upslanting palpebral fissures, epicanthal folds, midface hypoplasia, and small, dysplastic pinnae. Generalized hypotonia. Cognitive disabilities Congenital hea disease, most oftenly endocardial cushion defects or other septal defectsGastrointestinal tract anomalies including esophageal and duodenal atresias The affected newborn may have prolonged physiologic jaundice, polycythemia, and a transient leukemoid reaction. Leukemia is 12-20 times more common in Down syndrome patients. Ref: CURRENT Diagnosis Treatment: Pediatrics, 21e chapter 37. Fundamentals of Diagnostic Radiology edited by William E. Brant, page 927 