FGFR3 and achondroplasia: These mice recapitulate the disproportionate shortening of the limbs, kyphosis, and midface hypoplasia observed in ACH patients, but unlike humans and other ACH murine models, expression of 2 FGFR3-G380R alleles (FGFR3G380R/G380R) is required for maximum skeletal reductions in these animals (10).