The role of the analysis of sialotransferrin isoforms in the management of hereditary fructose intolerance: a systematic review.

Background: Untreated patients affected by hereditary fructose intolerance (HFI) present an abnormal transferrin (Tf) glycosylation pattern suggestive of N-hypoglycosylation. Analysis of defects in N-glycosylation is possible by analysis of serum sialotransferrin (sialoTf) pattern. The sialoTf profile is a valuable tool to facilitate the diagnosis of HFI. Its role in the monitoring of the diagnosed patients is less clear and debating.

Objectives And Methods: We examined the literature for the role of profile of serum sialoTf isoforms in monitoring HFI patients aiming at (1) providing an up-to-date summary of the available evidences on the impact of sialoTf isoforms in the follow-up of HFI patients; 2) evaluating the multifactorial effect of genotype and age at diagnosis on sialoTf isoforms; 3) assessing the relation between sialoTf isoforms and long-term liver complications. We used the GRADE approach to rank the quality of evidence.

Results: Nine full papers were identified according to our search criteria. Elevated serum carbohydrate-deficient Tf (CDT) fraction, disialoTf and tetrasialoTf/disialoTf ratio, and the asialoTf, tetrasialoTf and pentasialoTf + hexasialoTf isoforms appeared as the most reliable indicators for a follow up. No clear statistical correlation links sialoTf isoforms and liver damage. Age at diagnosis, potentially related to fructose tolerance, does not overtly impact sialoTf isoforms. Strong genotype-phenotype correlation has not been found so far.

Conclusions: There is no consensus about which isoform of sialoTf is more valuable for monitoring HFI patients. No clear correlation links sialoTf isoforms and liver damage, fructose tolerance and genotype. More robust studies are needed to provide conclusive results.