GLYCOSYLATED FERRITIN: A BIOMARKER TO HELP IN THE DIAGNOSIS OF FTL VARIANTS?

Aurélien COUETTE1, Salim ZERROUKI1, Houda HAMDI ROZE2,4, Lénaïck DETIVAUD2, Olivier LOREAL4, Marie-Laure ISLAND1, Edouard BARDOU JACQUET3,4, Martine ROPERT-BOUCHET1,4

1Department of Biochemistry Toxicology, University Hospital, Rennes, France
2Department of Molecular Genetic, University Hospital, Rennes, France
3Department of Liver Diseases, University Hospital, Rennes, France
4IINSERM, Univ Rennes, INRAe, UMR 1317, Nutrition, Metabolisms and Cancer institute (NuMéCan) , Rennes, France

Background :

The diagnosis of hyperferritinaemia related to FTL variants (Exon 1, IRE 5’ loop) is probably underdiagnosed. The aim of this study is to propose Glycosylated Ferritin (GlcFe) as a biochemical marker to aid in the diagnosis of unexplained hyperferritinaemia without iron overload.



Method:

Retrospective, observational, unicentric study since 2010 in a population of patients with hyperferritinaemia in whom GlcFe was measured by electrochemiluminescence after separation by ConcavalinA, compared with the clinico-biological and genetic diagnosis.



Results:

164 patients were included. In 21 Exon 1 patients, mean GlcFe was 98.9%±0.5 with mean total ferritin was 3811µg/l±3269. Mean GlcFe was 61.9%±7.4 in 25 IRE 5’ loop patients with mean total ferritin was 1400µg/l ±772. In 73 patients with metabolic hepatosiderosis, mean GlcFe was 81.6%6±7.1 with mean total ferritin was 713µg/l±251. While reference values ​​of GlcFe (67-88%) have been established for a healthy population (n=236), we also analysed 45 asymptomatic "control" patients with hyperferritinaemia and normal CRP in whom the mean GlcFe was 84.1%±4.7, and mean total ferritin was 457µg/L±180. We observed that 100% of patients diagnosed with an Exon 1 mutation had a GlcFe greater than 97%, while ferritin glycosylation was below 68% for 90% of patients diagnosed with IRE 5' loop mutation.



Conclusion:

The use of glycosylated ferritin would be a a simple and inexpensive first line biochemical test for the diagnosis of hyperferritinemia. A value greater than 97% or lower than 68%, this marker would suggest FTL sequencing with a high sensitivity and specificity.