A Japanese family with ferroportin disease caused by a novel mutation of SLC40A1 gene: hyperferritinemia associated with a relatively low transferrin saturation of iron.

Ferroportin disease, autosomal-dominant reticuloendothelial iron overload, may be more prevalent than hemochromatosis in Japan. Hyperferritinemia of 822 ng/ml with 24.8% transferrin saturation of iron was incidentally noted in a 43-year-old man. His iron overload was selective in Kupffer cells of the liver. Subsequently, his father was found to have asymptomatic hyperferritinemia of 2,283 ng/ml with 62.1% saturation. These affected subjects were heterozygous for 1467A>C (R489S) in SLC40A1, and without other mutations of the hemochromatosis genes. Here, we report a Japanese family with ferroportin disease, characterized by hyperferritinemia with relatively low transferrin saturations of iron.

Three patients with middle-age-onset hemochromatosis caused by novel mutations in the hemojuvelin gene.

Hemochromatosis is a genetically heterogeneous condition. Mutations in the recently described hemojuvelin gene were found in patients with juvenile hemochromatosis, who usually manifest clinical signs of iron overload, including cardiomyopathy and hypogonadism, in their teens and early 20s. In this report, we describe three Japanese patients who showed typical clinical and hepatic histological damage compatible with hemochromatosis at around 50 years of age. Genetic analyses showed that all three patients carried mutations in the hemojuvelin gene. The first patient was homozygous for a novel mutation (745G > C [D249H]), and the second and third patients from the same family were homozygous for another novel mutation (934C > T [Q312X]). No mutations in their HFE, hepcidin, transferrin receptor 2, or ferroportin genes were found. One patient had chronic infection with Helicobacter pylori. The age at initial presentation of hemojuvelin-hemochromatosis occurs over a wider range than previously described.

Two novel mutations, L490R and V561X, of the transferrin receptor 2 gene in Japanese patients with hemochromatosis.

BACKGROUND AND OBJECTIVES: The low prevalence of the C282Y mutation of the HFE gene in Japan means that the genetic background of hemochromatosis in Japanese patients remains unclear. In a previous report, we showed that 3 patients from one family had an AVAQ 594-597 deletion of the transferrin receptor (TfR2) gene. This suggests that the TfR2 gene is involved in hemochromatosis in Japanese patients. DESIGN AND METHODS: Nine patients clinically diagnosed with hemochromatosis were included in the study. DNA was extracted from whole blood samples collected with informed consent. The HFE and TfR2 genes were analyzed by sequencing the coding region and splicing sites. RESULTS: There were no mutations in the HFE gene. In the TfR2 gene, 2 novel mutations, 1469T->G (L490R) and 1665delC (V561X), were found in 2 patients. A known variation, 714C-> (I238M), was also found in the patient with L490R. The patient homozygous for both L490R and I238M presented with a mild manifestation of hemochromatosis at the age of 41 years. His liver was cirrhotic with parenchymal iron deposits and the result of a glucose tolerance test was compatible with diabetes mellitus. The patient homozygous for V561X had severe iron overload with the triad of cirrhosis, diabetes mellitus and skin pigmentation at the age of 58 years. INTERPRETATION AND CONCLUSIONS: Taken together with the previous report, 5 of our 12 patients with hemochromatosis manifesting in middle age had mutations in the TfR2 gene. Thus, TfR2 plays a role in the pathogenesis of hemochromatosis in Japan.