RYR1 and thymoma: First, thymomas–particularly WHO type B lesions–abnormally express muscle-derived autoantigens such as the acetylcholine-receptor α-subunit, ryanodine-receptor 1, and titin, providing high-affinity peptide substrates for the risk alleles HLA-DQB1*03:03 (class II), HLA-C*01:02 and HLA-B*52:01 (class I) (49).