Homozygous Genetic Hemochromatosis Research Articles

Reversibility of hepatic fibrosis in treated genetic hemochromatosis: A study of 36 cases

The current study was undertaken to assess whether fibrosis could regress under venesection therapy in patients with C282Y homozygous genetic hemochromatosis. The 36 patients studied were recruited from a subfile of our database consisting of 125 C282Y homozygotes with either severe fibrosis or cirrhosis (F3 or F4 fibrosis stage, respectively, according to the METAVIR grading system). The second liver biopsy was performed for management of liver cancer, extrahepatic surgery, or assessment of liver fibrosis. All paired biopsies were reviewed by two pathologists without knowledge of clinical data. Among the 13 patients who had F3 fibrosis on their initial liver biopsy, 3 had F0, 6 had F1, and 2 had F2 on their second liver biopsy. Among the 23 patients with cirrhosis on their initial liver biopsy, 1 had F0, 4 had F1, 3 had F2, and 2 had F3 on their second liver biopsy. When defining regression of fibrosis as a decrease of at least 2 METAVIR units, fibrosis regressed in 9 of 13 (69%) F3 and in 8 of 23 (35%) F4. When the ratio of gammaglobulins (g/L) to (platelets [n/mm(3)] x prothrombin activity [%]) was greater than 7.5, fibrosis never regressed. In conclusion, these data extend the concept of regression of fibrosis to patients with treated genetic hemochromatosis and suggest that some simple biochemical tests would be predictive of further regression of fibrosis as a result of venesection therapy. If confirmed on larger series, this could modify the ultrasound screening policy of hepatocellular carcinoma in genetic hemochromatosis.

Determination of Hepatic Iron Concentration in Fresh and Paraffin-embedded Tissue

Serum iron, transferrin, transferrin saturation, and ferritin are used to determine the iron status of an individual. When iron overload is suspected because of abnormal iron indices, the accurate determination of hepatic iron content (HIC) is important for the diagnosis of genetic hemochromatosis (GH). The measurement of HIC and the calculation of the hepatic iron index (HII), defined as HIC/age, enables the discrimination between patients with homozygous GH and those with either the heterozygous form of the disease or secondary causes of hepatic iron deposition. Despite the advent of DNA genotyping for the diagnosis of GH, liver biopsies are sometimes required for histological grading of liver disease and biochemical analysis to quantify the HIC. Genotyping will now identify many homozygotes before the development of clinical symptoms and an increased HII, and may reduce the need for obtaining a liver biopsy in some patients. However, in our experience the number of specimens submitted for HIC analysis has not changed over an 8-month period since the introduction of genotyping for GH. Two techniques are used for the determination of liver iron content. The more common technique is histological grading of stainable iron, using Prussian blue dye; the other technique is the quantitative chemical determination of iron. The latter requires the liver sample to be homogenized or digested with acid before iron determination by either colorimetry or atomic adsorption spectroscopy. The diagnosis of GH can be established reliably using the HII calculated from the hepatic iron concentration determined by atomic absorption spectroscopy. …

Monocyte-macrophage ferric reductase activity is inhibited by iron and stimulated by cellular differentiation.

The enzyme ferric reductase catalyses the reduction of Fe(III) as a prerequisite to its transportation across the cell membrane. Duodenal mucosal biopsies from iron overloaded patients with genetic haemochromatosis (GH) have increased ferric reductase activity and iron absorption compared with controls, yet the GH mucosa is iron deficient. A similar GH-related iron deficiency is also seen in macrophages. The aim of this study was to investigate whether macrophage ferric reductase activity is altered in GH, and to determine ferric reductase activity in monocytes and differentiated macrophages. The erythroleukaemic K562 cell line was studied as a clonal reference cell line. The basal K562 ferric reductase activity is characteristic of a membrane bound enzyme, being both temperature and protease sensitive. Ferric reductase activity was also demonstrated in human leucocyte, monocyte and macrophage preparations. Assays of K562 and macrophage cell supernatants confirmed that the ferric reductase activity was not due to a secreted factor. Assay of ferric reductase in normalized-iron and iron-enriched (100 microM ferric citrate) conditions showed no significant difference between Cys282Tyr (Cys282-->Tyr) homozygous GH macrophages and Cys282-Tyr negative control activities (P>0.05). However, a 900% increase in ferric reductase activity was observed during monocyte to macrophage differentiation (P<0.05), possibly reflecting the co-ordinate up-regulation of iron metabolism in these cells. The demonstration of approx. 25% activity after macrophage differentiation at high free-iron concentrations compared with 'normalized' iron is consistent with repression of human ferric reductase activity by iron. The identification of the human ferric reductase gene and its protein will ultimately provide insight into its regulation and role in mammalian iron metabolism.

HFE codon 63/282 (H63D/C282Y) dimorphism in German patients with genetic hemochromatosis.

Genetic hemochromatosis (GH) is closely associated with genes of the major histocompatibility complex (MHC) on chromosome 6. Recently, a candidate gene for GH, with structural similarities to MHC class I genes, designated HLA-H and presently named HFE, has been cloned. The HFE gene is localized telomeric to the MHC and several reports have indicated that the HFE gene is mutated in GH patients. In the present study we have analyzed the relationship of HFE gene variants and disease manifestation in GH patients and family members. Fifty-seven patients with GH, 73 family members and 153 healthy blood donors were studied for the amino acid dimorphism at codon 63 (His63Asp=H63D) and codon 282 (Cys282Tyr= C282Y) of the HFE gene. The codon 63 and 282 dimorphism were defined by PCR amplification of genomic DNA samples and restriction enzyme digestion using RsaI/SnaBI for C282Y and BclI/MboI for H63D. Ferritin, transferrin serum levels and total iron-binding capacity were determined prior to therapeutic intervention. The Tyr-282 substitution occurred in 53 (93%) of patients compared with 8 (5.2%) of controls (OR=169, P<0.0001). Fifty-one (90%) patients were Tyr-282 homozygous. In contrast, the Asp-63 substitution was present in 5 (8.8%) of the patients compared with 34 (22%) of controls (OR=0.39, P=NS) with none of the patients being homozygous. In Tyr-282 homozygous GH patients serum ferritin levels, transferrin saturation, liver iron and liver iron index were elevated significantly compared to Tyr-282-negative patients, whereas no difference was observed between Tyr/Cys-282 heterozygous and Tyr-282-negative patients.

Iron-rich foci in chronic viral hepatitis

Stainable iron in the liver (hemosiderosis) is most commonly seen in individuals with homozygous genetic hemochromatosis, prior transfusion, hemolysis, porphyria cutanea tarda, and chronic alcohol-induced liver disease. In chronic viral hepatitis, however, significant hepatocellular hemosiderosis is uncommon. This report describes unusual foci of hepatocellular hemosiderosis (“iron-rich foci” or IRF) in liver biopsy specimens from three patients with chronic hepatitis with or without cirrhosis (two hepatitis C-related, one hepatitis B-related). IRF present within the lobular parenchyma or cirrhotic nodules contrasted sharply with the immediately adjacent hemosiderinnegative liver tissue. Serum iron indices were abnormal in all three patients, but homozygous hemochromatosis was ruled out based on the hepatic iron concentration and hepatic iron index for each case. These cases highlight the potential for irregular iron storage in chronic viral liver disease and possible confusion with genetic hemochromatosis. The possible pathogenesis of IRF and the relationship of iron storage to the outcome of interferon therapy in chronic viral hepatitis are discussed.

Variability in hepatic iron concentration measurement from needle-biopsy specimens

Background/Aim: Quantitative measurement of hepatic iron by biochemical analysis of liver biopsy samples is required to assess hepatic iron stores accurately. Cirrhotic livers, however, contain variable amounts of fibrous tissue and the distribution of iron within the hepatic parenchyma is not always uniform. The aim of this study was to assess the variability in hepatic iron concentration measurement from needle-biopsy specimens. Methods: The livers from eight patients with cirrhosis selected because of elevated serum ferritin were obtained at the time of liver transplantation ( n=6) or at autopsy ( n=2). Multiple needle biopsies were done, and hepatic iron concentration was measured by atomic absorption spectroscopy. The hepatic iron index was calculated as iron concentration divided by age. Results: Four cases had a mean hepatic iron index above 2.0, in the range of that reported in patients with homozygous genetic hemochromatosis, whereas the other four had an hepatic iron index of less than 2.0. The intra-individual coefficient of variation for hepatic iron concentration ranged from 11.3 to 43.7%, averaging 24.9%. The coefficient of variation was smaller in biopsy samples > 4 mg dry weight than in samples <4 mg (19.8% vs 28.6%, p<0.05). Histological examination of surgical biopsies from these livers showed large amounts of fibrous tissue, and inhomogeneous distribution of iron in the hepatic parenchyma. Conclusions: This study demonstrates an important variability in the measurement of hepatic iron content from needle biopsy speciments in patients with severe cirrhosis.

The ancestral hemochromatosis haplotype is associated with a severe phenotype expression in Italian patients

We evaluate the relation between genotype and phenotype in 47 Italian male patients with homozygous genetic hemochromatosis (GH). Phenotype evaluation was based on the ratio of amount of iron removed (IR) by phlebotomy and age (IR/age). Patients were divided in two classes of phenotype expression: class I included 26 patients with less severe iron overload (IR/age ≤0.33) and class II included 21 patients with a more marked one (IR/age >0.33). Genetic variability was assessed by haplotype analysis combining alleles at HLA-B, D6S265, HLA-A, and D6S105 loci. A common ancestral haplotype carrying D6S265-1, HLA-A3, and D6S105-8 alleles was present in 13 of 52 (25%) chromosomes in class I and in 24 of 42 (57%) chromosomes in class II (P = .0027). Homozygotes and heterozygotes for the ancestral haplotype had higher iron indices than patients carrying two haplotypes other than the ancestral one. Seven of the eight patients homozygous for the ancestral haplotype were in class II, heterozygotes were equally distributed between the two classes, whereas 14 of 18 carriers of other haplotype combinations were in class I. Our results suggests that the gene defect linked to the ancestral haplotype is the result of a single, severe mutation. The high variability of phenotype expression in heterozygotes for the ancestral haplotype could be accounted for the contribution of the mutation carried by the second haplotype. Combination of different mutations could be responsible for the variable degrees of iron overload found in patients with GH. (Hepatology 1996 Jul;24(1):43-6)

The Ancestral Hemochromatosis Haplotype Is Associated With A Severe Phenotype Expression in Italian Patients

We evaluate the relation between genotype and phenotype in 47 Italian male patients with homozygous genetic hemochromatosis (GH). Phenotype evaluation was based on the ratio of amount of iron removed (IR) by phlebotomy and age (IR/age). Patients were divided in two classes of phenotype expression: class I included 26 patients with less severe iron overload (IR/age ≤0.33) and class II included 21 patients with a more marked one (IR/age &gt;0.33). Genetic variability was assessed by haplotype analysis combining alleles at HLA–B, D6S265, HLA–A, and D6S105 loci. A common ancestral haplotype carrying D6S265–1, HLA–A3, and D6S105–8 alleles was present in 13 of 52 (25%) chromosomes in class I and in 24 of 42 (57%) chromosomes in class II ( P = .0027). Homozygotes and heterozygotes for the ancestral haplotype had higher iron indices than patients carrying two haplotypes other than the ancestral one. Seven of the eight patients homozygous for the ancestral haplotype were in class II, heterozygotes were equally distributed between the two classes, whereas 14 of 18 carriers of other haplotype combinations were in class I. Our results suggests that the gene defect linked to the ancestral haplotype is the result of a single, severe mutation. The high variability of phenotype expression in heterozygotes for the ancestral haplotype could be accounted for the contribution of the mutation carried by the second haplotype. Combination of different mutations could be responsible for the variable degrees of iron overload found in patients with GH.

Liver fibrosis in genetic hemochromatosis: Respective roles of iron and non-iron-related factors in 127 homozygous patients

A retrospective study of 127 patients with untreated homozygous genetic hemochromatosis (HGH) was conducted to evaluate the respective roles of iron overload and non-iron-related factors in the development of hepatic fibrosis in HGH. Twenty-seven percent of the patients had cirrhosis, 21% had liver fibrosis and 52% had no fibrosis (prefibrotic group). The mean value of liver iron concentration was increased significantly (p < 0.001) in cirrhotic (378 +/- 144 mumol/g dry wt.) and in fibrotic (331 +/- 168) subjects compared to prefibrotic (237 +/- 108) patients. Of 13 patients with liver iron concentration > or = 500, 12 had liver fibrosis or cirrhosis, versus 48/134 with liver iron concentration < 500. Chronic alcoholic men exhibited hepatic fibrosis or cirrhosis more frequently than non-alcoholic men (p < 0.001). Non-alcoholic men had hepatic fibrosis or cirrhosis more often than non-alcoholic women (p < 0.05). Cirrhotic and fibrotic patients were significantly older than prefibrotic patients whilst a significant correlation between age and liver iron concentration was found in younger patients only. These results suggest that the iron overload threshold necessary to induce fibrosis is modulated by non-iron-related factors such as alcoholism, sex and age. The development of fibrosis in HGH with liver iron concentration < 500 mumol/g is frequent and must lead to a search for associated non-iron-related fibrogenic factors.

Hepatitis B virus infection markers in genetic haemochromatosis. A study of 272 patients.

Serum hepatitis B virus (HBV) infection markers were studied in 272 patients with homozygous genetic haemochromatosis complicated (n = 33) or not (n = 239) with primary liver cancer (PLC). Controls consisted of 255 029 healthy blood donors from whom age- and sex-matched control groups were extracted for statistical evaluation using the Fisher exact test. In blood donors, HBsAg was positive in 0.075% of males and 0.04% of females. This population was not screened for anti-Hbs. Anti-Hbc alone (without HBsAg) was present in 3.7% of men and 1.8% of women. In patients with genetic haemochromatosis without liver cancer (183 males, 45.6 +/- 11.3 yrs and 56 women, 48 +/- 12.4 yrs), HBsAg was found in 1.1% of men and in none of the women. Anti-HBs was present in 7.3% of males and 1.8% of females. Anti-HBc alone was found in 13% of males (p less than 0.005 vs. controls) and 2.1% of females. From male patients with primary liver cancer complicating genetic haemochromatosis (32 males, 61.7 +/- 6.8 yrs and one female), 6.2% were HBsAg positive, 3.4% were anti-HBs positive and 16.6% anti-HBc positive (p = 0.05 vs. controls). No serum HBV marker was found in the woman. In conclusion, the prevalence of HBV infection markers--especially anti-HBc--is significantly increased in patients with genetic haemochromatosis complicated or not with primary liver cancer.

Confirmation of the efficacy of hepatic tissue iron index in differentiating genetic haemochromatosis from alcoholic liver disease complicated by alcoholic haemosiderosis.

The hepatic tissue iron index proposed by Bassett et al was evaluated in 35 patients with homozygous genetic haemochromatosis, 67 patients with alcoholic liver disease, and 18 patients with other forms of chronic liver disease with and without cirrhosis. In patients with cirrhosis hepatic tissue iron concentration reliably differentiated alcoholic liver disease from genetic haemochromatosis. Although mean iron concentration was greater in patients with prefibrotic haemochromatosis than in those with prefibrotic alcoholic liver disease, some overlap occurred and complete differentiation of the two conditions was not possible. This overlap was particularly evident in some young patients with haemochromatosis in whom the tissue iron concentration grade fell in the range commonly seen in alcoholic haemosiderosis. Inability to differentiate early genetic haemochromatosis from alcoholic liver disease complicated by haemosiderosis was also a problem with standard Perls's staining. When the hepatic tissue iron index was calculated (hepatic tissue iron concentration/patient's age in years), clear differentiation of genetic haemochromatosis from both alcoholic liver disease and other forms of chronic liver disease was obtained in both cirrhotic and precirrhotic patients. This study confirms that the hepatic tissue iron index is a useful means of differentiating patients with genetic haemochromatosis from those with alcoholic liver disease. We suggest that biochemical estimation of tissue iron concentration and calculation of the tissue iron index in all patients in whom genetic haemochromatosis is a possible diagnosis will reduce the likelihood of misdiagnosing this as alcoholic liver disease.