Global Nell-1-overexpressing mice using a CMV promoter (CMV-Nell-1) exhibit phenotypes related to calvarial overgrowth and premature suture fusion without obvious extracranial abnormalities (despite verification of global Nell-1 transgene expression).(12) To determine whether Nell-1 can functionally compensate for some aspects of Runx2 deficiency (eg, CCD phenotype), Runx2+/− mice were mated to CMV-Nell-1 mice to generate Runx2+/−/CMV-Nell-1 mice. The gene discussed is RUNX2; the disease is cleidocranial dysplasia 1.