Down SyndromeSyndromeChromosomes, Human, Pair 21Prenatal DiagnosisTrisomyMaternal AgeMetabolic Syndrome XEstriolPregnancy Trimester, SecondPregnancyAmniocentesisLeukemia, Megakaryoblastic, AcuteFetal DiseasesChromosomes, Human, 21-22 and YNephrotic SyndromeAbortion, EugenicSjogren's SyndromeIntellectual DisabilityInfant, NewbornTurner SyndromeKaryotypingAbnormalities, Multiplealpha-FetoproteinsNasal BoneDisease Models, AnimalNuchal Translucency MeasurementNondisjunction, GeneticUltrasonography, PrenatalPregnancy, High-RiskPregnancy Trimester, FirstWilliams SyndromePhenotypeMyelodysplastic SyndromesPregnancy-Associated Plasma Protein-AChorionic Gonadotropin, beta Subunit, HumanCushing SyndromeFalse Positive ReactionsHeart Defects, CongenitalPaternal AgeAcute Coronary SyndromePolycystic Ovary SyndromeChromosome DisordersCase-Control StudiesRisk FactorsTime FactorsMutationDiGeorge SyndromeHorner SyndromeLong QT SyndromeCraniofacial AbnormalitiesPrader-Willi SyndromeBrainStanford-Binet TestBiological MarkersGenetic TestingHeart Septal DefectsAlzheimer DiseaseRetrospective StudiesGuillain-Barre SyndromeHemolytic-Uremic SyndromeDuodenal ObstructionPrevalenceCompartment SyndromesGATA1 Transcription FactorTourette SyndromeChorionic GonadotropinPorcine Reproductive and Respiratory SyndromePedigreeAntiphospholipid SyndromeGestational AgeMosaicismTreatment OutcomeMice, Inbred C57BLKlinefelter SyndromeMolecular Sequence DataNeckChromosome Aberrations