CFTR and cystic fibrosis: The lesson learned from these experiences is clear: although initiating CF NBS with the IRT biomarker alone is much better than no screening for CF, regions should plan from the outset on improving their laboratory methods, ideally with a DNA-based second-tier method as CFTR population data emerge and enable transformation to a better, DNA-based algorithm that can make CF NBS more worthwhile. Another alternative is to use pancreatitis-associated protein (PAP) as an adjunct but a variety of issues limit its effectiveness [14].