Juvenile hemochromatosis associated with heterozygosity for novel hemojuvelin mutations and with unknown cofactors.

BACKGROUND & AIMS: Juvenile hemochromatosis (JH) is a rare autosomal recessive disorder characterized by severe early-onset iron overload, caused by mutations in hemojuvelin (HJV), hepcidin (HAMP), or a combination of genes regulating iron metabolism. Here we describe two JH cases associated with simple heterozygosity for novel HJV mutations and unknown genetic factors. Case 1: A 12 year-old male from Central Italy with beta-thalassemia trait, increased aminotransferases, ferritin 9035 ng/ml and transferrin saturation 84%, massive hepatocellular siderosis and hepatic bridging fibrosis. Case 2: A 12 year-old female from Northern Italy with ferritin 467 ng/ml, transferrin saturation 87-95%, and moderate hepatic iron overload. MATERIAL AND METHODS: Direct sequencing of hemochromatosis genes (HFE-TfR2-HJV-HAMP-FPN-1) was performed in the children and siblings. RESULTS: In case 1, we detected heterozygosity for a novel HJV mutation (g.3659_3660insG), which was inherited together with the beta thalassemia trait from the father, who (as well as the mother) had normal iron parameters. In case 2, we detected another novel HJV mutation (g.2297delC) in heterozygosity, which was inherited from the mother, affected by mild iron deficiency. The father had normal iron stores. Both mutations are frameshifts determining premature stop codons. No other disease causing variant was detected. CONCLUSION: Although beta-thalassemia trait was a possible cofactor of iron overload in case 1, iron overload cannot be explained by simple heterozygosity for HJV mutations in both cases. Other genetic factors should be investigated, and further studies are needed to understand genotype-phenotype correlations in JH.

The A736V TMPRSS6 polymorphism influences hepatic iron overload in nonalcoholic fatty liver disease.

BACKGROUND & AIMS: Hepatic iron accumulation due to altered trafficking is frequent in patients with nonalcoholic fatty liver disease (NAFLD), and is associated with more severe liver damage and hepatocellular carcinoma. The p.Ala736Val TMPRSS6 variant influences iron metabolism regulating the transcription of the hepatic hormone hepcidin, but its role in the pathogenesis of iron overload disorders is controversial. Aim of this study was to evaluate the whether the TMPRSS6 p.Ala736Val variant influences hepatic iron accumulation in a well-characterized series of Italian patients with histological NAFLD. METHODS: 216 patients with histological NAFLD. TMPRSS6 and HFE variants were assessed by allele specific PCR, liver histology by the NAFLD activity score and Perls' staining for iron. RESULTS: Homozygosity for the p.736Val allele previously linked to higher hepcidin did not influence transferrin saturation (TS), but was associated with lower hepatic iron stores (p = 0.01), and ferritin levels (median 223 IQR 102-449 vs. 308 IQR 141-618 ng/ml; p = 0.01). Homozygosity for TMPRSS6 p.736Val was nearly associated with lower ballooning (p = 0.05), reflecting hepatocellular damage related to oxidative stress. The influence of TMPRSS6 on hepatic iron accumulation was more marked in patients negative for HFE genotypes predisposing to iron overload (p.Cys282Tyr + and p.His63Asp +/+; p = 0.01), and the p.736Val variant was negatively associated with hepatic iron accumulation independently of age, gender, HFE genotype, and beta-thalassemia trait (OR 0.59, 0.39-0.88). CONCLUSIONS: The p.Ala736Val TMPRSS6 variant influences secondary hepatic iron accumulation in patients with NAFLD.

Relative contribution of iron genes, dysmetabolism and hepatitis C virus (HCV) in the pathogenesis of altered iron regulation in HCV chronic hepatitis.

BACKGROUND AND OBJECTIVES: Hepatitis C virus (HCV) chronic hepatitis predisposes to iron overload, which negatively influences the prognosis of this infection. Since the underlying mechanisms of this iron overload are undefined, we analyzed the prevalence of altered iron parameters, and the relative contribution of viral, metabolic, and genetic factors in Italian patients. DESIGN AND METHODS: We studied the metabolic and biochemical characteristics of 143 previously untreated, biopsied patients with HCV who were not alcohol abusers. Hepatic iron was determined according to Deugnier, HFE genotype by restriction analysis, hepcidin, hemojuvelin, ferroportin-1, and transferrin receptor-2 mutations by denaturing high performance liquid chromatography and sequencing. RESULTS: Increased transferrin saturation was observed in 20%, hyperferritinemia in 22%, and histological iron deposition in 32% of patients. Ferritin was independently correlated with iron stores and host metabolic parameters, whereas hepatic iron deposition was correlated with ferritin and histological severity of hepatitis. Sinusoidal iron deposition was associated with metabolic alterations, including body mass index, insulin resistance, and LDL cholesterol. Conversely, the prevalence of HFE mutations and serum ferritin values increased with the severity of steatosis. The prevalence of HFE and beta-globin mutations was not different from that of controls (31% and 2%, respectively). No tranferrin receptor-2, hemojuvelin, or ferroportin-1 mutations were detected, but two patients carried the -72C>T hepcidin promoter mutation. The C282Y HFE mutation, hepcidin and beta-globin mutations influenced iron stores. Both carriers of the -72C>T Hepcidin mutation had beta-thalassemia trait, moderate iron overload, and liver cirrhosis. INTERPRETATION AND CONCLUSIONS: Iron genes influence iron overload and steatosis development, but the major burden is related to HCV itself and host metabolic factors.