To ascertain whether the mRNA downregulation of Cdk11 at the onset of T1D was causally related to beta cell death in vivo, we developed a NOD mouse model that was genetically hemideficient in CDK11 (N-HTZ) (Figure 2A), since the homozygous CDK11 deficiency is embryonically lethal (22). This evidence concerns the gene CDK19 and type 1 diabetes mellitus.