Recent studies have found strong associations of certain HLA alleles in diverse tissue-specific IgG4-mediated diseases, such as LGI1 encephalitis (DRB1*07:01–DQB1*02:02 haplotype) [10], anti-MusK myasthenia (DR14-DQ5 haplotype) [19], or anti-IgLON5 disease (DRB1*10:01-DQB1*05:01) [11]. This evidence concerns the gene IGLON5 and glycogen storage disease VI.