Hereditary iron overload is associated with mutations in a number of genes involved in the regulation of iron metabolism. In this study we examined the molecular basis of iron overload in an individual from New Zealand and characterised the molecular and cellular defect.
We analysed the ferroportin gene and a control population was screened using allele-specific PCR and denaturation analysis. Molecular characterisation was performed by immunofluorescence microscopy analysis of transfected cells. We analysed the ferritin levels of cells expressing wild-type and mutant ferroportin to define the nature of the molecular defect on iron transport.
We identified a novel nucleotide substitution (c. 1014T>G) in the ferroportin gene leading to the S338R mutation. This mutation is not a common polymorphism. Cellular analysis of the mutant protein indicates that this amino acid change does not affect the localisation of the protein or its ability to transport iron.
The S338R mutation results in a mutated ferroportin associated with iron overload and is predicted insensitive to regulation by the iron regulatory hormone hepcidin.