Journal Article

International Myasthenia Gravis Genomics Consortium, et al. Identification of genetic risk loci and prioritization of genes and pathways for myasthenia gravis: a genome-wide association study,Identification of genetic risk loci and prioritization of genes and pathways for myasthenia gravis: a genome-wide association study

Kaminski, Henry J., Evoli, Amelia, Petrucci, Loredana, Sanders, Donald B., Benatar, Michael, Siddiqi, Zaeem, Koopman, Wilma J., Chopra, Manisha, Freimer, Miriam, Mezei, Michelle M., Pliner, Hannah A., Barohn, Richard J., Florence, Julaine, Oger, Joel, Muppidi, Srikanth, Chaudhry, Vinay, McVey, April, Chia, Ruth, Abramzon, Yevgeniya, Blackmore, Derrick, De Rosa, Anna, Massey, Janice M., Provenzano, Carlo, Ricciardi, Roberta, Wulf, Charlie, Roda, Ricardo H., Soloway, Aimee, Jiwa, Theresa, Sabatelli, Mario, Saez-Atienzar, Sara, Nicolle, Michael W., Wolfe, Gil, Drachman, Daniel B., Todi, Laura, Marino, Mariapaola, Lipscomb, Bernadette, Rosa, Anna De, Pestronk, Alan, Tienari, Pentti J., Guida, Melania, Traynor, Bryan J., Howard, James F., Richman, David P., Blauwendraat, Cornelis, Corse, Andrea, Murphy, Natalie, Chiò, Adriano, Pasnoor, Mamatha, Pascuzzi, Robert M., Rowin, Julie, Dimachkie, Mazen M., Renton, Alan E., Kissel, John T., Maestri, Michelangelo

2022

Overview

Our study, involving 1,873 patients and 36,370 healthy individuals, is an extensive genome-wide study of myasthenia gravis. Our genome-wide association and transcriptome-wide association analyses identified two signals, namely CHRNA1 and CHRNB1 , encoding acetylcholine receptor subunits, which were replicated in an independent cohort obtained from the UK Biobank. Identifying these genes confirms the potential utility of using genetics to identify proteins that are the antigenic targets of autoantibodies. We confirmed that the genetic abnormalities underlying early-onset and late-onset myasthenia gravis are different. Our data offer a broader insight into the genetic architecture underlying the pathophysiology of myasthenia gravis. Myasthenia gravis is a chronic autoimmune disease characterized by autoantibody-mediated interference of signal transmission across the neuromuscular junction. We performed a genome-wide association study (GWAS) involving 1,873 patients diagnosed with acetylcholine receptor antibody-positive myasthenia gravis and 36,370 healthy individuals to identify disease-associated genetic risk loci. Replication of the discovered loci was attempted in an independent cohort from the UK Biobank. We also performed a transcriptome-wide association study (TWAS) using expression data from skeletal muscle, whole blood, and tibial nerve to test the effects of disease-associated polymorphisms on gene expression. We discovered two signals in the genes encoding acetylcholine receptor subunits that are the most common antigenic target of the autoantibodies: a GWAS signal within the cholinergic receptor nicotinic alpha 1 subunit ( CHRNA1 ) gene and a TWAS association with the cholinergic receptor nicotinic beta 1 subunit ( CHRNB1 ) gene in normal skeletal muscle. Two other loci were discovered on 10p14 and 11q21, and the previous association signals at PTPN22 , HLA-DQA1/HLA-B , and TNFRSF11A were confirmed. Subgroup analyses demonstrate that early- and late-onset cases have different genetic risk factors. Genetic correlation analysis confirmed a genetic link between myasthenia gravis and other autoimmune diseases, such as hypothyroidism, rheumatoid arthritis, multiple sclerosis, and type 1 diabetes. Finally, we applied Priority Index analysis to identify potentially druggable genes/proteins and pathways. This study provides insight into the genetic architecture underlying myasthenia gravis and demonstrates that genetic factors within the loci encoding acetylcholine receptor subunits contribute to its pathogenesis.