Universal newborn screening for CF has been in place in the United states since 2010; all states use immunoreactive trypsinogen (IRT) as the initial screen followed by either repeat IRT (IRT/IRT) or DNA-based testing (IRT/DNA) as the follow-up screen.15 Separate from IRT-based newborn screening, a distinct second prompt for CF diagnosis is the presence of symptomatic disease.9,16 In either scenario, CFTR genetic testing has been employed as part of the diagnostic follow-up to another prompt for more than 20 years. This evidence concerns the gene CFTR and cystic fibrosis.