Mice, KnockoutHeterozygoteMice, Inbred C57BLMice, TransgenicMice, Mutant StrainsDisease Models, AnimalAnimals, NewbornHomozygoteRats, Mutant StrainsPhenotypeGene TargetingBody WeightRNA, MessengerLiverGene Expression RegulationMice, Inbred StrainsBehavior, AnimalCrosses, GeneticImmunohistochemistryGene ExpressionMice, 129 StrainTransgenesOrgan Size