Novel mutations of the ferroportin gene (SLC40A1): analysis of 56 consecutive patients with unexplained iron overload.

The aim of this study was to search for SLC40A1 mutations in iron overloaded patients, which tested negative for HFE mutations and other iron-related genes. After a careful differential diagnosis, we selected 56 patients with unexplained iron overload whose phenotype could suggest the ferroportin disease. Iron overload was assessed by liver biopsy or by superconducting quantum interference device. SLC40A1 exons and intron-exon boundaries were amplified by polymerase chain reaction and sequenced. We also evaluated the presence of the insulin-resistance hepatic iron overload and of non-alcoholic fatty liver disease. Iron status was assessed in 44 families. We identified two novel mutations (D157N and V72F) at the heterozygous state in two probands. Phenotype heterogeneity was observed in both families, suggesting variable penetrance and expression. Including the two affected ones, 25 of the 44 families (57%) available for the iron study had one or more relatives with increased serum iron indices. Our findings not only suggest that the presence of major alterations of serum iron parameters in probands' relatives is a main criteria to improve the power of the genetic testing for ferroportin disease but also indicate that a number of patients exists in which the etiology of iron overload remains still undefined.