IGHG3 and type 1 diabetes mellitus: Moreover, pediatric subjects with recent-onset T1D demonstrated elevated serum levels of the alpha cytoplasmic isoform of Hsp90 compared to age and sex-matched controls [6], while elevated levels of circulating IgG1 and IgG3 class-switched anti-Hsp90 autoantibodies have been identified in individuals with T1D [10].