CFTR and cystic fibrosis: Newborn screening for cystic fibrosis (CF) was introduced in 1988 and, similar to the two-tiered approach for hemoglobinopathy screening, utilized DNA extraction from DBS and assessment for common pathogenic variants in the CFTR gene after a positive first-tier screen, in this case with immunoreactive trypsinogen (IRT) as the first step in screening (15).