A development of atypical immune microenvironments in the thymus with germinal center formation, B cell maturation, and ectopic neuromuscular expression of GABRA5, MAP2, NEFL, NEFM, SOX15 by neuromuscular mTECs (KRT6+ GABRA5+ nmTECs) was described for MG-associated thymomas (226, 227). The gene discussed is GABRA5; the disease is myasthenia gravis.