Type 1 diabetes (T1D) results from autoimmune-mediated destruction of insulin-producing pancreatic β cells. While there is a genetic component to T1D, there is no reliable way to identify which genetically at-risk individuals will develop autoantibodies. In this episode, Mark Harris, Ahmed Mehdi, and Ranjeny Thomas discuss their work, which identifies a gene expression signature during infancy that when combined with HLA risk score predicts later seroconversion in genetically at-risk subjects. Use of this signature has potential to improve early diagnosis and treatment intervention for those at risk of developing T1D.
Autoimmune-mediated destruction of pancreatic islet β cells results in type 1 diabetes (T1D). Serum islet autoantibodies usually develop in genetically susceptible individuals in early childhood before T1D onset, with multiple islet autoantibodies predicting diabetes development. However, most at-risk children remain islet-antibody negative, and no test currently identifies those likely to seroconvert. We sought a genomic signature predicting seroconversion risk by integrating longitudinal peripheral blood gene expression profiles collected in high-risk children included in the BABYDIET and DIPP cohorts, of whom 50 seroconverted. Subjects were followed for 10 years to determine time of seroconversion. Any cohort effect and the time of seroconversion were corrected to uncover genes differentially expressed (DE) in seroconverting children. Gene expression signatures associated with seroconversion were evident during the first year of life, with 67 DE genes identified in seroconverting children relative to those remaining antibody negative. These genes contribute to T cell–, DC-, and B cell–related immune responses. Near-birth expression of ADCY9, PTCH1, MEX3B, IL15RA, ZNF714, TENM1, and PLEKHA5, along with HLA risk score predicted seroconversion (AUC 0.85). The ubiquitin-proteasome pathway linked DE genes and T1D susceptibility genes. Therefore, a gene expression signature in infancy predicts risk of seroconversion. Ubiquitination may play a mechanistic role in diabetes progression.
Ahmed M. Mehdi, Emma E. Hamilton-Williams, Alexandre Cristino, Anette Ziegler, Ezio Bonifacio, Kim-Anh Le Cao, Mark Harris, Ranjeny Thomas