What difference is seen in the interpretation of results in states that offer IRT-DNA newborn screening for CF versus IRT only?

a. Carrier status can be determined by IRT-DNA screening.
b. IRT-only testing results in extremely low false positive results vs IRT-DNA screening.
c. A sweat chloride test would not be indicated in IRT-only screening.
d. IRT is highly specific and rarely is elevated except in the presence of CF.