A tri-modal distribution of age-of-onset in female patients with myasthenia gravis is associated with the gender-related clinical differences

AbstractBackground: A tri-modal distribution of age-at-onset emerged among females patients with myasthenia gravis (MG) in our database. This finding may be indicative of different gender-based disease mechanisms.Methods: We retrospectively reviewed the files of 127 MG patients for the clinical, serology and thymus pathology according to their age at disease onset: ≤40 years (early-onset, EOMG), 40–70 years (intermediate-onset, IOMG) and >70 years (late-onset, LOMG).Results: EOMG was more common among females, and IOMG was more common among males. Ocular MG was more common among the male MG patients with an IOMG. Patients with EOMG had lower rates of positive anti-acetylcholine receptor (anti-AChR). IOMG females, but not IOMG males, had lower rates of positive anti-AChR. IOMG and EOMG females had high rates of thymic hyperplasia, while EOMG males had high rates of thymoma. Comorbidity with autoimmune diseases was common among females with IOMG and LOMG.Conclusions: The prevalence of IOMG was the reason fo...