With the exception of the atypical nuclear receptors dosage-sensitive sex reversal-adrenal hypoplasia congenital critical region on the X chromosome, gene 1 (DAX1, encoded by NR0B1) and small heterodimer partner (SHP, encoded by NR0B2), all other nuclear receptors share four to five common domains labeled A–F. The gene discussed is NR0B1; the disease is chronic primary adrenal insufficiency.