CNP and Severe short stature: Targeted disruption of the Nppc or Npr2 genes (encoding CNP and GC-B, respectively) lead to achondroplasia, dwarfism, female infertility and early death [5,6], and these severe growth phenotypes in mice are mirrored by the symptoms of human patients with inactivating mutations in NPR2 and NPPC mutations [7,8].