PTPN22 and rheumatoid arthritis: This gene has been shown to be associated with several other autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematosus, Graves' disease, Addison's disease, and myasthenia gravis, suggesting a general role of LYP in the autoimmune process [21], and the current exome analysis supports results obtained by other studies which showed a strong relationship between PTPN22 and T1D [22].