Patients with MG may be associated with autoimmune as well as non-autoimmune comorbidities. Autoimmune comorbidities such as autoimmune thyroiditis, followed by systemic lupus erythematosus, and rheumatoid arthritis have been reported as the most frequent comorbidities of MS. 361 Co-occurrence of thymoma MG and late-onset MG with cardiomyositis and subclinical cardiac dysfunction have been reported, however, these conditions have not been considered a significant risk. Lymphomas and some other cancers have been documented with a slightly higher frequency, autoimmune MG does not appear to be a separate cancer risk factor. 361 MG has been reported in 0.2% of the diagnosed cases of autoimmune thyroid disease. Pernicious anemia, psoriasis, systemic vasculitis, and other disorders have also been reported. The prevalence of autoimmune comorbidity is different for MG subtypes: individuals with early-onset MG are more likely to develop an additional autoimmune disease than those with lateonset MG. Another group of diseases co-occurring frequently with MG are cardiovascular diseases. Arterial hypertension is noted to prevail in patients with MG. With respect to cancers lymphoma, breast cancer, and lung cancer have been found more common in the group of MG patients. Mental health disorders such as depression and anxiety are frequent among MG patients. Concurrent MG and ALS have also been registered in many cases. The results of examination of co-occurrences of ALS, HD, and MG terms with other rare and non-rare diseases in the CAS Content Collection are illustrated in Figure . ALS and HD most frequently co-occurs with Alzheimer's, and Parkinson's diseases, and multiple sclerosis, as well as between themselves. MG most frequently co-occurs with multiple sclerosis, rheumatoid arthritis, and systemic lupus erythematosus (Figure ).