Newborn screening for carnitine palmitoyltransferase II deficiency using (C16+C18:1)/C2: Evaluation of additional indices for adequate sensitivity and lower false-positivity.

•Despite the high frequency among fatty acid oxidation disorders, newborn screening for CPT II deficiency has not been fully established.•The ratio of (C16+C18:1) to C2 in newborn dried blood specimens can serve as a useful index provided that the cutoff is set sufficiently low.•In order to achieve adequate sensitivity to avoid false-negative cases, a considerable increase in false-positive cases seems inevitable.•Using additional indices such as C14/C3 is a promising way of reducing the false-positive rate.