This glycoform, corresponding to the biantennary truncated N-glycan NeuAc1Gal1Man3GlcNAc4 lacking one terminal NeuAc-Gal epitope, has been explicitly addressed to a distinctive serum N-glycome signature for B4GALT deficiency in SLC39A8-CDG patients [5]. The gene discussed is B4GALNT2; the disease is hyperinsulinemic hypoglycemia, familial, 4.