Modeling on the success of fluid-phase islet antibody assays that are the gold-standard assay format for diagnosing T1D and for identifying individuals at risk of developing T1D in clinical prevention trials [55], we developed similar radioimmunoprecipitation assays using in vitro transcribed and translated cDNAs encoding full-length (FL) human α-MyHC (MYH6), FL β-MyHC (MYH7)—the major MyHC isoform expressed in human heart ventricle—human α-actinin 2 (ACTN2), and cardiac troponin I (TNNI3). This evidence concerns the gene TNNI3 and type 1 diabetes mellitus.