First, to determine the number of gene knockouts that result in a body mass phenotype, we needed to define a more precise phenotype. The Mammalian Phenotype Ontology52 (http://www.informatics.jax.org/searches/MP_form.shtml) specifies a controlled vocabulary by which all mice in the MGI database are classified. Within this framework, (we believed) the most applicable is “abnormal postnatal growth/weight/body size” (MP:0002089).
