CFTR and cystic fibrosis: NBS programs using a more limited second-tier CFTR variant panel should consider using the VHIRT strategy and include an unequivocal and obvious alert in the NBS report that a risk of CF may be present, especially if there is a family history of CF or if the infant has signs and symptoms of CF, including but not restricted to persistent diarrhea, poor weight gain, salt loss syndrome, chronic cough, or respiratory problems.