Thymic disorders and myasthenia gravis: genetic aspects

Myasthenia gravis (MG) is an autoimmune disease characterized by production of antibodies to acetylcholine receptor at the motor end-plate responsible for impairment of neuromuscular transmission. There is general agreement a bout the involvement of the thymus in the pathogenesis of MG, and thymic pa thological changes are commonly found in MG patients. Genetic factors seem to play an important role in susceptibility to MG. As with other autoimmune diseases, genetic predisposition to MG probably involves multiple genes. A mple evidence suggests that genes within the major histocompatibility compl ex (MHC) are involved in susceptibility to autoimmune diseases. Both data f rom the literature and our findings indicate that different genes within th e MHC could predispose to various forms of MG, and that particularly the tu mour necrosis factor genes may play a role in the association between the d ifferent thymic disorders and MG.