The British Columbia newborn screening program introduced a three-tier screening algorithm (IRT-DNA-IRT) for Cystic Fibrosis, using a second IRT measurement at three weeks of age for all individuals with one mutation on CFTR testing or an initial IRT in the top 0.1% and no CFTR mutations, screening over 400,000 infants from 2010–2018 (Figure 1). This evidence concerns the gene CFTR and cystic fibrosis.