Donors at risk for type 1 diabetes were identified as in Methods based on donor positivity for insulin autoantibody (IAA) plus at least one other islet autoantibody and PBMCs were flow cytometry sorted to identify IgM+ and/or IgD+, IgD- CD27- memory, or CD27+ memory B cells and stimulated as in Methods (Figure 5A). This evidence concerns the gene CD27 and type 1 diabetes mellitus.