In this study, we could not identify the plasma N‐pentasaccharide glycan in Control (n = 40), in all patients with ALDOB deficiency/hereditary fructose intolerance (HFI) (n = 4), PMM2‐CDG (n = 11), MPI‐CDG (n = 5), ALG3‐CDG (n = 5), MPDU1‐CDG (n = 1), DPM1‐CDG (n = 1), DPM3‐CDG (n = 1), SRD5A3‐CDG (n = 10), DOLK‐CDG (n = 8), RFT1‐CDG (n = 2), ALG11‐CDG (n = 2), ALG12‐CDG (n = 4), ALG13‐CDG (n = 1), ALG9‐CDG (n = 3), ALG6‐CDG (n = 4), ALG8‐CDG (n = 4), DPAGT1‐CDG (n = 3), and SSR4‐CDG (n = 1) as well as in patients from our previous glycomics cohort of PGM1‐CDG and CDG type 2 (CDG‐II).10, 13. This evidence concerns the gene RFT1 and hyperinsulinemic hypoglycemia, familial, 4.