Increased susceptibility to nonalcoholic fatty liver disease in heterozygotes for the mutation responsible for hereditary hemochromatosis

BACKGROUND: Insulin resistance is a key feature of nonalcoholic fatty liver disease. Patients with hereditary hemochromatosis, a disease characterized by progressive iron overload due, in most cases, to homozygosity for C282Y mutation in the HFE gene, have often decreased insulin sensitivity and release. AIMS: To determine whether increased iron parameters/heterozygosity for the mutations of the HFE gene confer susceptibility to nonalcoholic fatty liver disease. PATIENTS: One hundred and thirty-four consecutive Italian patients with clinical and ultrasonographic diagnosis of nonalcoholic fatty liver disease (82 with hyperferritinemia), half confirmed by liver biopsy. METHODS: Insulin was determined by radioimmunoassay. HFE gene mutations were determined by polymerase chain reaction and restriction fragment length polymorphism analysis. RESULTS: (1) Prevalence of C282Y HFE mutation was significantly higher in patients with nonalcoholic fatty liver disease compared to controls, the difference being more striking in patients with hyperferritinemia than in those without. (2) The presence of mild iron overload was associated with a lower insulin release. (3) Carriers of C282Y mutation developed nonalcoholic fatty liver disease despite lower body mass index and triglycerides. CONCLUSION: The mild iron overload associated with heterozygosity for C282Y HFE mutation confers susceptibility to nonalcoholic fatty liver disease, causing relative insulin deficiency.     

Nonalcoholic steatohepatitis in Asian Indians is neither associated with iron overload nor with HFE gene mutations

AIM: The pathogenesis of occurrence of liver inflammation and fibrosis in patients with nonalcoholic steatohepatitis (NASH) is not completely understood. Other than insulin resistance, iron abnormalities have been thought to be one of the triggering factors. Therefore, our aim was to study the role of iron abnormalities and HFE gene mutations in patients with NASH. METHODS: Thirty-one patients of NASH diagnosed on the basis of clinical examination biochemistry, ultrasonography and liver biopsy (n = 14) were included in the study. Serum iron parameters (n = 23) (iron, ferritin, total iron-binding capacity and transferrin saturation), Perls' iron staining on liver biopsies (n = 14) and HFE gene mutations (C282Y and H63D) (n = 16) were studied in these patients. The association between iron staining, necroinflammatory activity and fibrosis stage on liver biopsies was also determined. RESULTS: Elevated serum iron, ferritin and transferrin saturation above 55% were observed in 4.3% of patients. On histology, 71% of the patients had negative iron staining, 21.4% had 1+ staining, 7.2% had 2+ staining and none had 3+ or 4+ staining. There was no association between the degree of iron staining and necroinflammatory activity (P=0.55) and fibrosis stage (P= 0.09) on histology. None of the patients had C282Y HFE gene mutation and four patients (25%) were found to be heterozygotes for H63D gene mutation. CONCLUSION: Our study does not favor iron overload and HFE gene mutations as major factors in the pathogenesis of NASH in Asian Indians.     

C282Y and H63D mutations in the HFE gene have no effect on iron overload disorders in Japan

OBJECTIVE: The gene responsible for hereditary hemochromatosis close to the human leukocyte antigen A locus was previously identified and designated as HFE. This study was performed to evaluate the clinical significance of two mutations, C282Y and H63D of HFE, in Japanese patients with hepatic iron overload. PATIENTS AND METHODS: We examined C282Y and H63D in 11 patients with primary hemochromatosis, 94 patients with chronic hepatitis C, 54 patients with miscellaneous liver diseases, and 151 healthy volunteers. The HFE gene region of DNA samples extracted from peripheral leukocytes was amplified by polymerase chain reaction. Restriction enzyme analysis was performed using SnaBI for C282Y and BclI for H63D. Direct sequence analysis was then performed when products suggested the presence of a mutation. RESULTS: All the subjects studied were free from C282Y. None of the patients with hemochromatosis had H63D. One patient with chronic hepatitis C was homozygous, and 4 patients were heterozygous for H63D. Two patients with alcoholic liver disease were heterozygous for H63D. The prevalence of chromosomes with H63D was 6/188 (3.2%) in patients with chronic hepatitis C, 2/108 (1.9%) in patients with miscellaneous liver diseases, and 8/302 (2.6%) in healthy volunteers. These differences were not significant. CONCLUSION: Our results suggested that neither C282Y nor H63D in HFE affect Japanese patients with hemochromatosis or chronic hepatitis C.     

Heterozygosity for the hemochromatosis gene in liver diseases--prevalence and effects on liver histology

BACKGROUND/AIMS: The effect of heterozygosity for the C282Y mutation in the HFE hemochromatosis gene on iron accumulation and disease progression in liver disease patients is unclear. METHODS: We investigated the prevalence of this mutation in 531 patients and 205 healthy controls. In addition, we assessed the influence of the mutation on liver histology in 34 C282Y heterozygous and 124 age-, sex- and disease-matched controls without the mutation using the modified HAI and Chevallier score. RESULTS: The highest prevalence of the C282Y mutation was observed in patients with autoimmune hepatitis (17.2%, p<0.01) compared to 6.4% in healthy controls. Heterozygotes with hepatitis C and B virus infection showed higher ferritin and hepatic iron concentrations than patients without the mutation. However, we did not detect significant differences in necroinflammatory or fibrosis scores between carriers of the mutation and controls. CONCLUSIONS: There are marked differences in the prevalence of the C282Y mutation in patients with different liver diseases, with the highest prevalence rates in autoimmune hepatitis and PBC. However, the C282Y mutation alone only leads to a mild increase in iron accumulation in the majority of the patients, with the exception of H63D/C282Y compound heterozygotes. We found no evidence for more pronounced fibrosis in C282Y heterozygotes.     

The effect of the metabolic syndrome, hepatic steatosis and steatohepatitis on liver fibrosis in hereditary hemochromatosis.

OBJECTIVES: The variability in phenotypic expression of hereditary hemochromatosis (HH) is not fully understood. We sought to examine whether the metabolic syndrome, hepatic steatosis or steatohepatitis influenced hepatic fibrosis among patients with HH and iron overload. METHODS: We identified 86 patients with C282Y/C282Y or C282Y/H63D HH and iron overload (hepatic iron concentration (HIC) >2,200 microg/g for males, >1,600 microg/g for females). Features of the metabolic syndrome were assessed at the time of liver biopsy. Biopsies were scored by a blinded pathologist. Significant fibrosis was defined as peri-portal fibrosis or greater. RESULTS: The mean (+/-SD) age of the study population was 53+/-12 years and 68 (79%) were male. The median (range) values of ferritin and HIC were 1,125 (253-9,530) microg/l and 9963 (1926-50 887) microg/g, respectively. The metabolic syndrome was present in 23 (27%), hepatic steatosis in 43 (50%), steatohepatitis in 18 (21%) and significant fibrosis in 38 (44%). Overall, neither the metabolic syndrome nor any of its components were associated with significant fibrosis or a higher mean fibrosis stage. Hepatic steatosis but not steatohepatitis was associated with a lower fibrosis stage. C282Y/H63D compound heterozygous individuals who had glucose intolerance had more severe fibrosis compared with those without glucose intolerance (1.0+/-1.0 vs. 0.1+/-0.3, P=0.01). CONCLUSIONS: Overall, the metabolic syndrome and fatty liver were not associated with hepatic fibrosis among individuals with HH and iron overload. However, glucose intolerance may be important risk factor for the development of hepatic fibrosis in subjects with the C282Y/H63D HFE genotype.     

Heterozygosity for the hemochromatosis gene in liver diseases – prevalence and effects on liver histology

Abstract: Background/Aims: The effect of heterozygosity for the C282Y mutation in the HFE hemochromatosis gene on iron accumulation and disease progression in liver disease patients is unclear. Methods: We investigated the prevalence of this mutation in 531 patients and 205 healthy controls. In addition, we assessed the influence of the mutation on liver histology in 34 C282Y heterozygous and 124 age‐, sex‐ and disease‐matched controls without the mutation using the modified HAI and Chevallier score. Results: The highest prevalence of the C282Y mutation was observed in patients with autoimmune hepatitis (17.2%, p<0.01) compared to 6.4% in healthy controls. Heterozygotes with hepatitis C and B virus infection showed higher ferritin and hepatic iron concentrations than patients without the mutation. However, we did not detect significant differences in necroinflammatory or fibrosis scores between carriers of the mutation and controls. Conclusions: There are marked differences in the prevalence of the C282Y mutation in patients with different liver diseases, with the highest prevalence rates in autoimmune hepatitis and PBC. However, the C282Y mutation alone only leads to a mild increase in iron accumulation in the majority of the patients, with the exception of H63D/C282Y compound heterozygotes. We found no evidence for more pronounced fibrosis in C282Y heterozygotes.     

Hemochromatosis in Ireland and HFE

ABSTRACT: Sixty patients diagnosed with hereditary hemochromatosis with grade 3 or 4 hepatic iron overload and 18 patients diagnosed with hereditary hemochromatosis who had less than grade 3 hepatic iron overload were examined for theHFEgene mutations, 845A (C282Y) and 187G (H63D). Control samples were obtained from 109 randomly selected individuals. Fifty-six of 60 unrelated hereditary hemochromatosis patients (93%) with grade 3 or 4 hepatic iron deposition were homozygous for the C282Y mutation. Fourteen of the 18 hereditary hemochromatosis patients with <3+ iron deposition (76%) were homozygous for the C282Y mutation. Three of 8 patients who were heterozygous for the C282Y mutation were also heterozygous for the H63D mutation. Thirty-one of 109 control individuals were heterozygous for the C282Y mutation and 27 were heterozygous for the H63D mutation. Our finding that 93% of hereditary hemochromatosis patients who fulfil standard diagnostic criteria are homozygous for the C282Y mutation provides clear evidence that this mutation is strongly associated with hereditary hemochromatosis. The allele frequency of 14% for the C282Y mutation in our control population is the highest reported and supports the hypothesis of a Celtic origin for the hereditary hemochromatosis gene.     

Common heterozygous hemochromatosis gene mutations are risk factors for inflammation and fibrosis in chronic hepatitis C.

BACKGROUND: Chronic hepatitis C is frequently associated with increased hepatic iron stores. It remains controversial whether heterozygous mutations of hemochromatosis genes affect fibrosis progression. Therefore our aim was to assess associations between HFE mutations and hepatic inflammation and stage of fibrosis in German hepatitis C patients. METHODS: Liver biopsies from 166 patients were scored for inflammatory activity (A0-4) and hepatic fibrosis (F0-4). Gene mutations were determined by LightCycler, restriction fragment length polymorphism analysis, or direct sequencing. RESULTS: The frequencies of common HFE mutations C282Y and H63D are 4.2% and 21.3%, whereas the recently described S65C substitution and the Y250X mutation in the transferrin receptor 2 gene are very rare. In regression analysis, heterozygous carriers of C282Y or H63D mutations display significantly (P < 0.05) higher inflammatory activities and more advanced fibrosis than patients without mutations. For C282Y heterozygous patients, the odds ratios for marked inflammatory activity (A2-4) and advanced liver fibrosis or cirrhosis (F2-4) are 4.9 and 4.6, respectively, compared with patients carrying homozygous wild-type alleles. C282Y mutations are associated with significantly (P < 0.05) increased serum iron and aminotransferase levels, whereas H63D heterozygotes display higher transferrin saturation, serum iron, and ferritin concentrations compared to wild-type (P < 0.01). CONCLUSIONS: Common heterozygous hemochromatosis mutations are associated with higher grades of inflammation and more severe hepatic fibrosis. Our findings support a role of HFE mutations as primary risk factors for fibrogenesis and disease progression in chronic hepatitis C.     

A Chinese patient with non-HFE-linked iron overload.

The gene for hemochromatosis (HFE) was recently identified and contains two missense mutations: C282Y and H63D. The C282Y mutation is found homozygous in approximately 85% to 90% of patients of Northern European ancestry with hereditary hemochromatosis. There are no previous reports with results of genetic testing in Chinese patients with regard to iron overload. In this case report, we describe a Chinese woman with marked hepatic iron overload that was nonfamilial, with unusual biopsy findings, in whom neither the C282Y nor the H63D mutations in HFE were found.     

Hyperferritinemia, iron overload, and multiple metabolic alterations identify patients at risk for nonalcoholic steatohepatitis

OBJECTIVE: The aim of this study was to define in patients with hyperferritinemia and normal transferrin saturation the relationships among hyperferritinemia, iron overload, HFE gene mutations, the presence of metabolic alterations, and nonalcoholic steatohepatitis (NASH). METHODS: Forty patients with increased serum ferritin, resistant to dietary restriction and normal transferrin saturation, 90 with ultrasonographic evidence of hepatic steatosis, and 60 obligate heterozygotes for hemochromatosis, all negative for alcohol abuse, hepatitis virus infections, and inflammation were studied. Transferrin saturation, serum ferritin, uric acid, lipids, glucose tolerance, insulin resistance, HFE gene mutations, liver histology, and hepatic iron concentration were analyzed. RESULTS: Of the 40 patients with hyperferritinemia, 29 (72%) had biochemical metabolic abnormalities, 18 of the 26 examined (69%) had insulin resistance, 26 (65%) had the presence of one of the two HFE gene mutations (normal controls, 33 of 128 [26%], p < 0.0001), and all had increased liver iron concentration. Thirty-one patients (77%) had histology compatible with NASH. At univariate analysis, NASH was significantly associated with the presence of metabolic alterations, the C282Y mutation, and severity of fibrosis. At multivariate analysis, NASH was associated with the coexistence of multiple metabolic alterations (odds ratio = 5.2, 95% CI = 0.95-28.7). The risk of having NASH augmented in the presence of higher values of ferritin and liver iron concentration. Among the 90 patients with ultrasonographic evidence of hepatic steatosis, 24 (27%) had increased serum ferritin with normal transferrin saturation, but only six remained hyperferritinemic after dietary restriction. CONCLUSION: Increased ferritin with normal transferrin saturation is frequently found in patients with hepatic steatosis, but it reflects iron overload only in those patients in whom it persists despite an appropriate diet. The simultaneous disorder of iron and glucose and/or lipid metabolism, in most of the cases associated with insulin resistance, is responsible for persistent hyperferritinemia and identifies patients at risk for NASH.     

Genetic hemochromatosis and the HFE gene: from molecular genetics to clinical diagnosis

More than 90% of patients with genetic hemochromatosis carry a characteristic mutation in the HFE-gene (C282Y). HFE modulates the iron uptake by the transferrin receptor. Duodenal crypt cells of HFE-knockout mice show low intracellular iron concentrations which lead to an upregulation of the divalent metal transporter and enhanced iron uptake by duodenal enterocytes. Heterozygosity for the C282Y mutation appears to alter the course of other liver diseases like porphyria cutanea tarda and nonalcoholic steatohepatitis.     

Two novel nonsense mutations of HFE gene in five unrelated italian patients with hemochromatosis

BACKGROUND & AIMS: Most hemochromatosis patients of Northern European descent are homozygous for the C282Y mutation of HFE gene. In Italy, many patients with iron overload are not homozygous for C282Y, and the presence of other mutations or other genetic determinant has been suggested. METHODS: Five unrelated Italian patients heterozygous for C282Y with the classic hemochromatosis phenotype were studied. The entire coding sequence and the exon-intron boundaries of the HFE gene were analyzed. Chromosome 6p haplotypes were defined in each patient by analysis of D6S265, D6S105, and D6S1281 microsatellites. RESULTS: Two novel nonsense HFE mutations were identified in exon 3 in the C282Y negative chromosome. The first one, a G-to-T transition at codon 168, was detected in 3 probands; the second, a G-to-A transition at codon 169, was detected in the others. CONCLUSIONS: The 2 nonsense mutations in the compound heterozygous state with C282Y result in the classic hemochromatosis phenotype in several unrelated Italian patients. This confirms that hemochromatosis in Italy is not as homogeneous as in northern Europe and suggests that other mutations can exist in C282Y or H63D heterozygotes with iron overload. These findings have practical implications for diagnostic and screening strategies for hemochromatosis.     

HFE mutations,hepatic iron,and fibrosis: ethnic-specific association of NASH with C282Y but not with fibrotic severity

There is conflicting evidence regarding inheritance of hemochromatosis gene (HFE) mutations and influence of hepatic iron deposition as cofactors for development of fibrosis in patients with nonalcoholic steatohepatitis (NASH). We studied hepatic iron content (Perls' stain grade), frequency of HFE mutations, and serum iron indices in 93 patients with NASH from a multiethnic background; 59 (63%) were of Anglo-Celtic origin. Data on C282Y mutations were available for all 93 patients and on H63D for 69 patients. Respective controls were 206 (for C282Y, 141 [69%] of whom were Anglo-Celtic) and 180 (for H63D) blood donors. Hyperferritinemia was present in 38 patients (40%) with NASH, but transferrin saturation was increased (>55%) in only 5 (5%). Liver biopsy specimens showed advanced fibrosis in 31 (33%) (cirrhosis in 20%). Altogether, 9 biopsy specimens (10%) showed increased iron: 7 (8%) with grade 2 and 2 (2%) with grade 3 iron staining. Only 1 biopsy specimen with increased iron showed advanced fibrosis. The frequency of C282Y heterozygosity was increased in Anglo-Celtic patients with NASH compared with ethnic blood donor controls (22% vs. 9.2%; P =.035); there were no C282Y homozygotes in the NASH cohort. Although there was a trend toward higher serum ferritin levels among C282Y heterozygotes with NASH, there were no differences in histologic grades of steatosis, inflammation, or fibrosis between individuals with and without C282Y. The frequencies of compound C282Y/H63D heterozygotes (n = 1) or H63D heterozygotes (n = 10) were not increased in NASH. Multivariate analysis identified female sex, diabetes mellitus, and more severe liver inflammation but not HFE mutations, serum ferritin, iron saturation, or hepatic iron staining as independent predictors of hepatic fibrosis. In conclusion, hepatic iron is not a factor linked to hepatic fibrogenesis in patients with NASH. HFE mutations do not confer an additional risk of hepatic fibrosis in this disorder.     

Significance of H63D homozygosity in a Basque population with hemochromatosis

Background: The significance of H63D homozygosity remains uncertain, although it is associated with a tendency for patients to develop iron overload. Aims: To study the prevalence of homozygotic H63D mutation in patients with phenotypic hemochromatosis (PH) and to compare the results with those of the general population and with patients with porphyria cutanea tarda (PCT) in the Basque Country, Spain. A secondary aim was to evaluate the differences in phenotypic expression and liver injury according to different genotypes in the PH cohort. Methods: Mutations of the HFE gene were obtained by polymerase chain reaction (PCR). Forty consecutive patients diagnosed with PH, 116 controls and 54 patients with PCT were included in the study. We performed liver biopsies, measured liver iron concentration (LIC), by atomic spectrophotometry, serum ferritin and transferrin saturation, and compared the histology according to the genotype. Results: The H63D homozygote mutation was identified in 7.76% of the control group, in 7.50% of the PH group, and in 11.11% of patients with PCT (P > 0.05). The C282Y/C282Y mutation was present in 50% of patients with PH, and LIC was identified in 15/20. The LIC in C282Y/C282Y patients was higher than in H63D/H63D patients (P = 0.26), while H63D homozygosis caused greater iron overload in PH patients than other genotypes. All the C282Y/C282Y genotype patients had elevated serum ferritin and transferrin saturation. The H63D homozygotes had high ferritin, but two out of three had normal transferrin saturation. Six of the eight patients with high‐grade fibrosis and genetic study results were found to be C282Y/C282Y. Conclusions: The prevalence of H63D mutation in patients with PH in our region does not differ from that of the general Basque population.     

Gender-related variations in iron metabolism and liver diseases

The regulation of iron metabolism involves multiple organs including the duodenum, liver and bone marrow. The recent discoveries of novel iron-regulatory proteins have brought the liver to the forefront of iron homeostasis. The iron overload disorder, genetic hemochromatosis, is one of the most prevalent genetic diseases in individuals of Caucasian origin. Furthermore, patients with non-hemochromatotic liver diseases, such as alcoholic liver disease, chronic hepatitis C or nonalcoholic steatohepatitis, often exhibit elevated serum iron indices (ferritin, transferrin saturation) and mild to moderate hepatic iron overload. Clinical data indicate significant differences between men and women regarding liver injury in patients with alcoholic liver disease, chronic hepatitis C or nonalcoholic steatohepatitis. The penetrance of genetic hemochromatosis also varies between men and women. Hepcidin has been suggested to act as a modifier gene in genetic hemochromatosis. Hepcidin is a circulatory antimicrobial peptide synthesized by the liver. It plays a pivotal role in the regulation of iron homeostasis. Hepcidin has been shown to be regulated by iron, inflammation, oxidative stress, hypoxia, alcohol, hepatitis C and obesity. Sex and genetic background have also been shown to modulate hepcidin expression in mice. The role of gender in the regulation of human hepcidin gene expression in the liver is unknown. However, hepcidin may play a role in gender-based differences in iron metabolism and liver diseases. Better understanding of the mechanisms associated with gender-related differences in iron metabolism and chronic liver diseases may enable the development of new treatment strategies.     

Porphyria cutanea tarda in Brazilian patients: association with hemochromatosis C282Y mutation and hepatitis C virus infection

OBJECTIVE: Porphyria cutanea tarda (PCT) is commonly associated with iron overload and hepatitis C virus (HCV) infection. Association between hemochromatosis C282Y or H63D mutations and PCT has been observed, although not uniformly, and iron overload is also commonly found in chronic HCV hepatitis. The aim of the present study was to investigate the frequency of C282Y and H63D mutations and HCV infection in Brazilian patients with PCT and their relationship with iron overload. METHODS: Twenty-three patients (19 men) aged 39.6 +/- 11.1 yr were studied. All had dermatological lesions of PCT and high levels of urinary uroporphyrin. HCV infection and iron overload were investigated. DNA samples were analyzed for the presence of HFE mutations. RESULTS: The frequency of C282Y was significantly higher in PCT patients than in 278 healthy individuals (17.4% vs 4%, odds ratio = 5.1, 95% confidence interval 1.5-17.6, p = 0.02), whereas no difference was observed regarding the H63D mutation (30.4% vs 31%, odds ratio = 1, 95% confidence interval 0.4-2.4, p = 1). Biochemical tests in PCT patients showed iron overload with transferrin saturation = 47.3 +/- 20.7% and ferritin = 566.8 +/- 425 ng/ml. Fifteen of 23 (65.2%) patients had HCV infection and alcohol ingestion was observed in 17 of 23 (73.9%). CONCLUSIONS: PCT patients exhibited evidence of iron overload, a high frequency of HCV, and an association with C282Y mutation. These data further support the notion that both acquired and inherited factors contribute to the occurrence of PCT, and indicate that screening for C282Y may be justified in PCT patients.     

Prevalence and clinical significance of HFE gene mutations in patients with iron overload

OBJECTIVE: The HFE gene contains two mutant alleles; C282Y and H63D. The C282Y mutation occurs in 55-100% of patients with hereditary hemochromatosis. The aim of our study was to re-examine the frequencies of the C282Y and H63D mutations in patients with mild and marked iron overload and in normal subjects. METHODS: A total of 82 patients with iron overload were included in this study and had hepatic iron index determination and/or quantitation of iron stores by phlebotomy. The control group consisted of 81 healthy blood donors. HFE mutation analysis was performed on leukocyte DNA using PCR-amplified genomic DNA. RESULTS: Of patients with iron overload, 70/82 (85%) were homozygous for C282Y versus 2/81 (2.5%) in the control population. Four patients had no HFE mutations despite significant iron overload, including a sister and brother (brother not included in the study group) with hepatic iron concentrations >500 micromoles/g dry weight. CONCLUSIONS: In all, 85% of our patients with iron overload were C282Y homozygotes, although a few had no HFE gene mutations. Pooled data and analysis of chromosomes considered to be at risk for H63D indicate that H63D is associated with iron overload.     

Screening for hemochromatosis in asymptomatic subjects with or without a family history

BACKGROUND: Hemochromatosis in white subjects is mostly due to homozygosity for the common C282Y substitution in HFE. Although clinical symptoms are preventable by early detection of the genetic predisposition and prophylactic treatment, population screening is not currently advocated because of the discrepancy between the common mutation prevalence and apparently lower frequency of clinical disease. This study compared screening for hemochromatosis in subjects with or without a family history. METHODS: We assessed disease expression by clinical evaluation and liver biopsy in 672 essentially asymptomatic C282Y homozygous subjects identified by either family screening or health checks. We also observed a subgroup of untreated homozygotes with normal serum ferritin levels for up to 24 years. RESULTS: Prevalence of hepatic iron overload and fibrosis were comparable between the 2 groups. Disease-related conditions were more common in male subjects identified by health checks, but they were older. Hepatic iron overload (grades 2-4) was present in 56% and 34.5% of male and female subjects, respectively; hepatic fibrosis (stages 2-4) in 18.4% and 5.4%; and cirrhosis in 5.6% and 1.9%. Hepatic fibrosis and cirrhosis correlated significantly with the hepatic iron concentration, and except in cases of cirrhosis, there was a 7.5-fold reduction in the mean fibrosis score after phlebotomy. All subjects with cirrhosis were asymptomatic. CONCLUSIONS: Screening for hemochromatosis in apparently healthy subjects homozygous for the C282Y mutation with or without a family history reveals comparable levels of hepatic iron overload and disease. Significant hepatic fibrosis is frequently found in asymptomatic subjects with hemochromatosis and, except when cirrhosis is present, is reversed by iron removal.     

Iron in nonhemochromatotic liver disorders

Iron is essential for cellular functions, but in excessive amounts it is toxic to cells. The harmful effects are related to increased oxidative stress and production of reactive oxygen species causing oxidative damage to lipids, proteins, and nucleic acids. Heavy iron overload as occurs in primary and secondary hemochromatosis can cause fibrosis of various parenchymal organs such as the liver, heart, and pancreas. Lesser degrees of hepatic iron deposition are also associated with, and seem to be risk factors for, certain nonhemochromatotic liver diseases. Porphyria cutanea tarda is associated with hepatic iron overload and responds to iron-reduction therapy. Other recent evidence indicates that the prevalence of HFE gene mutations is increased in chronic viral hepatitis and that patients with chronic hepatitis C harboring especially the C282Y mutation are more likely to suffer from advanced hepatic fibrosis or cirrhosis and to do so at younger ages. In this article we review selected nonhemochromatotic disorders in which iron can play an important comorbid role.     

Transferrin receptor-2 gene and non-C282Y homozygous patients with hemochromatosis

More than 80% of the patients affected by hereditary hemochromatosis, a common inherited iron disorder, are homozygotes for the 845G --> A (C282Y) mutation of the HFE gene. However, depending on the population, 10-20% of hereditary hemochromatosis can be linked either to other HFE genotypes, particularly the compound heterozygous state for C282Y and the 187 C --> G (H63D) mutation, or to mutations of new other genes. Recently, Camaschella et al. (Nat. Genet. 25, 14-15, 2000) identified a stop mutation (exon 6 nt 750 C --> T, Y250X) on the transferrin receptor-2 (TFR2) gene in two unrelated Sicilian families with hereditary hemochromatosis. The TFR2 gene is a transferrin receptor gene homologue that seems to be involved in iron metabolism. Moreover, one of the patients described by Camaschella et al. was a H63D homozygote. H63D homozygosity can be associated with various phenotypes from asymptomatic subjects to patients with a typical form of hereditary hemochromatosis. Thus, the Y250X mutation could be the molecular defect responsible for hereditary hemochromatosis in subjects with atypical HFE genotypes. We have searched for the Y250X mutation in 63 unrelated French subjects. Forty-three had a diagnosis of hereditary hemochromatosis based on classical criteria. This group included 12 H63D homozygotes, 3 C282Y heterozygotes, and 3 patients with none of the two most prevalent HFE mutants. These 18 patients had no other HFE sequence change and were subsequently subjected to DNA sequencing of the 15 last exons and flanking sequences of the TFR2 gene. The 25 remaining hereditary hemochromatosis patients who were tested for the Y250X mutant were compound heterozygotes for the C282Y and H63D mutations. Finally, we also tested for this TFR2 mutation 20 H63D homozygotes with milder manifestations of iron overload and no acquired cause of iron overload. None of the 63 tested subjects had the Y250X mutation. Concurrently, none of the 18 hereditary hemochromatosis patients who had their TFR2 gene sequenced had any deleterious mutation. Thus, TFR2 mutations are not responsible for hemochromatosis in non-C282Y homozygous patients of our area.