CFTR and myotonic dystrophy type 1: All these hESC lines were derived previously in our laboratory30; VUB01 and VUB02 were derived from embryos donated by infertile patients, and characterized as genetically normal, whereas VUB03 was derived from an embryo shown to be affected with myotonic dystrophy type 1 (VUB03_DM1), and VUB04 from an embryo with the F508del mutation in one copy of the CFTR gene and the 5 T variant in the second allele (VUB04_CF).