We also observed that, intriguingly, both patients with AChR-MG and those with MuSK-MG showed an enrichment of IgG4 (Figure 6B, fold change of mean IgG4/IgG ratio in patients compared to non-disease controls: AChR = 2.58; AChR + IS = 2.17; MuSK = 2.91; MuSK + IS = 2.40), with no significant difference between MuSK-MG and AChR-MG. The gene discussed is MUSK; the disease is myasthenia gravis.