Overlap of Genetic Susceptibility to Type 1 Diabetes, Type 2 Diabetes, and Latent Autoimmune Diabetes in Adults

Despite the notion that there is a degree of commonality to the biological etiology of type 1 diabetes (T1D) and type 2 diabetes (T2D), the lack of overlap in the genetic factors underpinning each of them suggests very distinct mechanisms. A disorder considered to be at the “intersection” of these two diseases is “latent autoimmune diabetes in adults” (LADA). Interestingly, genetic signals from both T1D and T2D are also seen in LADA, including the key HLA and transcription factor 7-like 2 (TCF7L2) loci, but the magnitudes of these effects are more complex than just pointing to LADA as being a simple admixture of T1D and T2D. We review the current status of the understanding of the genetics of LADA and place it in the context of what is known about the genetics of its better-studied “cousins,” T1D and T2D, especially with respect to the myriad of discoveries made over the last decade through genome-wide association studies.