Gene DosageDosage Compensation, GeneticPhenotypeMutationGene DuplicationAllelesMolecular Sequence DataGene Expression Regulation, DevelopmentalBase SequenceDosage FormsGenesChromosome MappingGene DeletionGenes, FungalSaccharomyces cerevisiaeTranscription FactorsGene Expression ProfilingHeterozygoteMice, TransgenicPlasmidsGene ExpressionModels, GeneticGene Expression RegulationX Chromosome InactivationTranscription, GeneticRNA InterferenceHomozygoteGenomicsGenotypeX ChromosomeDrosophila ProteinsDrosophilaCrosses, GeneticGene TargetingDrosophila melanogasterOligonucleotide Array Sequence AnalysisTransgenesGenetic TechniquesHomeodomain ProteinsDown SyndromeGene SilencingRNA, MessengerGenes, LethalRecombination, GeneticEvolution, MolecularTrisomyMultigene FamilyMutagenesis, InsertionalMorphogenesisAneuploidyCloning, MolecularSuppression, GeneticChromosomes, Human, Pair 21DNA-Binding ProteinsHaploinsufficiencyGenes, PlantMice, Inbred C57BLMice, Mutant StrainsDNA Transposable ElementsEscherichia coliDatabases, GeneticIntegrasesGenetic Complementation TestAmino Acid SequencePolyploidyComputational BiologyGenes, RegulatorPolymerase Chain ReactionGenes, BacterialGenetic VectorsPromoter Regions, GeneticGene Expression Regulation, PlantMice, KnockoutIn Situ Hybridization, FluorescenceSaccharomyces cerevisiae ProteinsGenes, InsectTransformation, GeneticSequence Analysis, DNAPAX2 Transcription FactorAnimals, Genetically ModifiedArabidopsisZebrafishMutagenesisGene Expression Regulation, FungalGenomeFungal ProteinsRepressor ProteinsGene AmplificationGenes, X-LinkedMolecular Sequence AnnotationPhylogenyDNACaenorhabditis elegansEmbryo, NonmammalianChromosomesGenes, HomeoboxExonsChromosomes, BacterialEmbryo, MammalianDNA Mutational Analysis