New Insights Into the Genetics of Autoimmune Myasthenia Gravis: An Evolving Story

Acquired myasthenia gravis (MG) is the prototypic neurologic autoimmune disease. The disease is unlike congenital myasthenic syndromes, where mutations in different genes encoding molecules important in the neuromuscular junction cause major changes in function and are inherited in classic mendelian patterns. Such mutations are not readily seen in patients with autoimmune MG, a complex disorder in which small changes in genes, called single-nucleotide polymorphisms (SNPs), in multiple genes and perhaps minor changes in the products of those genes seem to be involved in the pathogenesis of the disease. Using arrays with the potential to interrogate a million or more SNPs and modern high-power computing capacity allows analysis of a large number of genes in a very large number of patients with a particular disease and control individuals without having to preselect candidates of interest. This approach, called genome-wide association studies (GWAS), has been used extensively to examine the genome of individuals with a wide variety of diseases including neurologic and immune-mediated diseases. In multiple sclerosis (MS), more than 110 candidate variants have been identified, the overwhelming majority of associated genes are involved in the immune system, in particular T cells.¹ This is important in MS, where autoimmunity has not been completely established as the primary cause of the disease.