DLK1 and type 1 diabetes mellitus: The Kubicek lab published the first application of single-cell transcriptomics to human islet cells in 2016 (103); while the number of beta-cells identified was extremely low, they showed transcriptome heterogeneity for genes such as DLK1, a T1D associated gene by GWAS (Genome-Wide Association Study) which will be discussed later in more detail.