The Proteomics Study of Compounded HFE/TF/TfR2/HJV Genetic Variations in a Thai Family with Iron Overload, Chronic Anemia, and Motor Neuron Disorder

Abstract

The mutation of the homeostatic iron regulatory genes (HFE) impaired the hepatic hepcidin transcription leading to the chronic excess of the iron pool, with the adverse consequences of free radical oxidative damages. We herein reported the findings of Thai family members who had the compound of uncommon HFE rs2794719, together with transferrin (TF) rs1867504, transferrin receptor 2 (TfR2) rs7385804, and hemojuvelin (HJV) rs16827043 genetic variants involved in the hepcidin transcriptional pathway. These compounded genetic variants could produce the spectrum of clinical phenotypes that spanned from mild to moderate symptoms of chronic anemia to an established motor neuron disorder. The feasible pathophysiologies were the impairment of the transferrin receptor functions, which affected the endocytic uptake of halo-transferrin into the erythroblast precursors. Such a defect left the erythropoiesis depleted of their iron supply. These alterations also promoted the TfR-independent uptake of iron into other target tissues and left the TrF2/BMP-dependent-hepcidin activation pathway unattended. We used the predicted molecular interactive proteomes to support our speculated dysregulated iron metabolism. During the early stage of an elevated ferritin level, there was no inhibition of ferroportin activities from hepcidin. These pathophysiological processes went on to the point of an iron overload threshold. After that, the hepcidin transcription started to kick in with the resulting decreased serum iron levels and deterioration of clinical symptoms.