Compared to sporadic PHPT, parathyroid disease in MEN1 occurs at an earlier age (20–25 years of age vs. 55 years) with an equal male to female ratio (1:1 vs. 1:3), and typically has multiple gland involvement, with ultimate involvement of all four glands (as compared to 80–85% of patients with sporadic PHPT that have single gland disease). The gene discussed is MEN1; the disease is parathyroid gland disorder.