However, since 2018, when the nationwide NBS for CPT II deficiency started, the number of false-positive results for not only (C16 + C18:1)/C2 but also C14/C3 increased, many of which were caused by very low levels of C3 (Supplementary Figure S1). This evidence concerns the gene CPT2 and hyperinsulinemic hypoglycemia, familial, 4.