NR0B2 and chronic primary adrenal insufficiency: Except for the dose-sensitive sex reversal-adrenal hypoplasia congenital critical region on the X chromosome, gene 1 (DAX1) and the small heterodimer partner (SHP), all NRs are typically single-chain polypeptides that share four or five functional domains,68 including the N-terminal transcription activation domain (NTD), the DNA-binding domain (DBD), the ligand-binding domain (LBD), the C-terminal transcription activation domain (CTD) and a hinge domain (H) that connects the DBD and LBD (Fig. 2).