Inclusion Criteria:  Age from 16 years and older. Gender: both sexes are included.  Clinical Diagnosis of MG with supporting evidence as:  unequivocal clinical response to pyridostigmine decrement >10% in repetitive nerve stimulations study (RNS). Willingness to sample collection, imaging study and other disease-related examinations and assessments.  Exclusion Criteria:  Age younger than 16 years. History of chronic psychiatric or neurological disorder other than MG that can produce weakness or fatigue. Severe systemic illness affecting life-expectancy.