Bulk RNAseq in islets from CF vs. non-CF donors revealed no significant changes in expression of key β cell transcription factors (MAFA, NKX6.1, PDX1, PAX6, ISL1) or components of the β cell secretory pathway (INS, SLC2A2, SLC2A1, GCK, ABCC8, GLP1R) (30). This evidence concerns the gene ISL1 and cystic fibrosis.