She had a heterozygous CB TF phenotype, a condition that regularly yields low CDT values, but she showed consistently high serum %CDT values together with an abnormal [[alpha].sub.1]-AT IEF profile, findings that were finally attributed to a generalized disturbance in N-glycosylation caused by CDG-Ia
Patients with the CDG-Ia subtype had the highest amounts of disialo(range, 19-42%) and asialotransferrin (3.4-26%), whereas the patients with type Ib and Ig CDG had less asialotransferrin (<3%; Table 1).
The CDG type I pattern resembles that observed after chronic alcohol consumption (CDT), albeit the relative increases were much higher in CDG-Ia. In a previous study, four of six carriers of one CDG-Ia mutation (healthy parents of CDG patients) had increased asialo-and disialotransferrin concentrations indistinguishable from the values observed in alcohol abuse (16).
High residual activity of PMM2 in patients' fibroblasts: possible pitfall in the diagnosis of CDG-Ia
These changes in pI and mass are consistent with the loss of a complex biantennary glycan, as was seen in some of the [[alpha].sub.1]-antitrypsin isoforms in CDG-Ia
. The substitution of a methionine for threonine at position 85 in [PIMZ.sub.Bristol] [[alpha].sub.1]-antitrypsin leads to the loss of a sequon for N-linked glycosylation, i.e., [NLT.sup.85]E [right arrow] [NLM.sup.85]E.