CFTR and cystic fibrosis: Although this case is complex as it seeks to diagnose a twin pregnancy, it demonstrates the potential of cell-based NIPT for prenatal testing of cystic fibrosis, where delta508 is a common variant constituting 88% of the CFTR variant alleles in the Danish population (Schwartz et al., 1990; Schwartz et al., 1992; de Boeck et al., 2014).