High-Throughput Approaches onto Uncover (Epi)Genomic Architecture of Type 2 Diabetes.

Type 2 diabetes (T2D) is a complex disorder that is caused by a combination of genetic, epigenetic, and environmental factors. High-throughput approaches have opened a new avenue toward a better understanding of the molecular bases of T2D. A genome-wide association studies (GWASs) identified a group of the most common susceptibility genes for T2D (i.e., TCF7L2 , PPARG , KCNJ1 , HNF1A , PTPN1 , and CDKAL1 ) and illuminated novel disease-causing pathways. Next-generation sequencing (NGS)-based techniques have shed light on rare-coding genetic variants that account for an appreciable fraction of T2D heritability ( KCNQ1 and ADRA2A ) and population risk of T2D ( SLC16A11 , TPCN2 , PAM , and CCND2 ). Moreover, single-cell sequencing of human pancreatic islets identified gene signatures that are exclusive to α-cells ( GCG , IRX2 , and IGFBP2 ) and β-cells ( INS , ADCYAP1 , INS-IGF2 , and MAFA ). Ongoing epigenome-wide association studies (EWASs) have progressively defined links between epigenetic markers and the transcriptional activity of T2D target genes. Differentially methylated regions were found in TCF7L2 , THADA , KCNQ1 , TXNIP , SOCS3 , SREBF1 , and KLF14 loci that are related to T2D. Additionally, chromatin state maps in pancreatic islets were provided and several non-coding RNAs (ncRNA) that are key to T2D pathogenesis were identified (i.e., miR-375). The present review summarizes major progress that has been made in mapping the (epi)genomic landscape of T2D within the last few years.