Arthropathy in hereditary haemochromatosis segregates with elevated erythrocyte mean corpuscular volume

Objective: To evaluate the relationship between erythrocyte parameters and the presence or absence of arthritis in HFE C282Y homozygous hereditary haemochromatosis (HH) subjects compared to control groups of non-HH subjects with arthritis.Method: Erythrocyte and arthritis parameters [mean corpuscular volume (MCV) and mean cell haemoglobin (MCH)] were obtained from consecutive HH subjects (n = 119) who were referred for initial evaluation and management. For comparison, MCV and MCH values were collected from randomly selected non-HH subjects with rheumatoid arthritis (n = 100) and osteoarthritis (n = 100), consisting of equal numbers of men and women. Two other comparison groups comprised 16 men and women who were heterozygous for C282Y with arthritis, and 38 non-HH subjects with type 2 polyarticular osteoarthritis (T2POA).Results: MCV values were significantly higher in HH subjects with arthritis (95 ± 0.56 fL) than in HH subjects without arthritis (92.75 ± 0.50 fL, p = 0.037). HH subjects with or without arthritis demonstrated a higher mean MCV than the control groups of non-HH osteoarthritis (90.12 ± 0.46 fL, p < 0.001) and non-HH rheumatoid arthritis (90.94 ± 0.57 fL, p < 0.001). HH subjects with arthritis also demonstrated a higher MCV than heterozygous C282Y subjects with arthritis (93.18 ± 1.55 fL, p = 0.025) and non-HH subjects with a similar pattern of arthritis, notably T2POA (91.13 ± 0.50 fL, p < 0.01). An MCV of ≥ 97.85 fL provided a likelihood ratio of 2.2 for development of arthritis in HH subjects.Conclusion: This study demonstrated a relationship between elevated MCV and arthritis in incident cases of HH.

Use of community genetic screening to prevent HFE-associated hereditary haemochromatosis

HFE-associated hereditary haemochromatosis is a recessive, iron-overload disorder that affects about one in 200 north Europeans and that can be easily prevented. However, genetic screening for this disease is controversial, and so we assessed whether such screening was suitable for communities. Cheek-brush screening for the Cys282Tyr HFE mutation was offered to individuals in the workplace. Outcomes were assessed by questionnaires before and after testing. 11,307 individuals were screened. We recorded no increase in anxiety in individuals who were homozygous for the Cys282Tyr mutation or non-homozygous. Self-reported tiredness before testing was significantly higher in homozygous participants than in non-homozygous participants (chi2 test, p=0.029). Of the 47 homozygous individuals identified, 46 have taken steps to treat or prevent iron accumulation. Population genetic screening for HFE-associated hereditary haemochromatosis can be practicable and acceptable.

A novel mutation in ferroportin1 is associated with haemochromatosis in a Solomon Islands patient

BACKGROUND

A severe form of iron overload with the clinicopathological features of haemochromatosis inherited in an autosomal dominant manner has been described in the Solomon Islands. The genetic basis of the disorder has not been identified. The disorder has similarities to type 4 haemochromatosis, which is caused by mutations in ferroportin1.

AIMS

The aims of this study were to identify the genetic basis of iron overload in a patient from the Solomon Islands.

PATIENT AND METHODS

Genomic DNA was isolated from peripheral blood leucocytes of a Solomon Islands man with severe iron overload. The entire coding region and splice sites of the ferroportin1 gene was sequenced.

RESULTS AND CONCLUSIONS

A novel missense mutation (431A>C; N144T) was identified in exon 5 of the ferroportin1 gene. A novel restriction endonuclease based assay which identifies both the N144T and N144H mutations was developed which will simplify the diagnosis and screening of patients for iron overload in the Solomon Islands and other populations. This is the first identified mutation associated with haemochromatosis in the Solomon Islands population.

Duodenal expression of iron transport molecules in untreated haemochromatosis subjects

BACKGROUND AND AIMS

In HFE associated hereditary haemochromatosis, the duodenal enterocyte behaves as if iron deficient and previous reports have shown increased duodenal expression of divalent metal transporter 1 (DMT1) and iron regulated gene 1 (Ireg1) in affected subjects. In those studies, many patients had undergone venesection, which is a potent stimulus of iron absorption. Our study investigated duodenal expression of DMT1 (IRE and non-IRE), Ireg1, hephaestin, and duodenal cytochrome-b (Dyctb) in untreated C282Y homozygous haemochromatosis patients, iron deficient patients, and iron replete subjects.

METHODS

Total RNA was extracted from duodenal biopsies and expression of the iron transport genes was assessed by ribonuclease protection assay.

RESULTS

Expression of DMT1 (IRE) and Ireg1 was increased 3-5-fold in iron deficient subjects compared with iron replete subjects. Duodenal expression of DMT1 (IRE) and Ireg1 was similar in haemochromatosis patients and iron replete subjects but in haemochromatosis patients with elevated serum ferritin concentrations, both DMT1 (IRE) and Ireg1 expression were inappropriately increased relative to serum ferritin concentration. Hephaestin and Dcytb levels were not upregulated in haemochromatosis. DMT1 (IRE) and Ireg1 levels showed significant inverse correlations with serum ferritin concentration in each group of patients.

CONCLUSIONS

These findings are consistent with DMT1 (IRE) and Ireg1 playing primary roles in the adaptive response to iron deficiency. Untreated haemochromatosis patients showed inappropriate increases in DMT1 (IRE) and Ireg1 expression for a given level of serum ferritin concentration, although the actual level of expression of these iron transport genes was not significantly different from that of normal subjects.

Effects of alcohol consumption on indices of iron stores and of iron stores on alcohol intake markers

BACKGROUND

Alcohol increases body iron stores. Alcohol and iron may increase oxidative stress and the risk of alcohol-related liver disease. The relationship between low or "safe" levels of alcohol use and indices of body iron stores, and the factors that affect the alcohol-iron relationship, have not been fully characterized. Other aspects of the biological response to alcohol use have been reported to depend on iron status.

METHODS

We have measured serum iron, transferrin, and ferritin as indices of iron stores in 3375 adult twin subjects recruited through the Australian Twin Registry. Information on alcohol use and dependence and smoking was obtained from questionnaires and interviews.

RESULTS

Serum iron and ferritin increased progressively across classes of alcohol intake. The effects of beer consumption were greater than those of wine or spirits. Ferritin concentration was significantly higher in subjects who had ever been alcohol dependent. There was no evidence of interactions between HFE genotype or body mass index and alcohol. Alcohol intake-adjusted carbohydrate-deficient transferrin was increased in women in the lowest quartile of ferritin results, whereas adjusted gamma-glutamyltransferase, aspartate aminotransferase, and alanine aminotransferase values were increased in subjects with high ferritin.

CONCLUSIONS

Alcohol intake at low level increases ferritin and, by inference, body iron stores. This may be either beneficial or harmful, depending on circumstances. The response of biological markers of alcohol intake can be affected by body iron stores; this has implications for test sensitivity and specificity and for variation in biological responses to alcohol use.

Lipid peroxidation in hepatic steatosis in humans is associated with hepatic fibrosis and occurs predominately in acinar zone 3

BACKGROUND AND AIMS

Hepatic steatosis has been shown to be associated with lipid peroxidation and hepatic fibrosis in a variety of liver diseases including non-alcoholic fatty liver disease. However, the lobular distribution of lipid peroxidation associated with hepatic steatosis, and the influence of hepatic iron stores on this are unknown. The aim of this study was to assess the distribution of lipid peroxidation in association with these factors, and the relationship of this to the fibrogenic cascade.

METHODS

Liver biopsies from 39 patients with varying degrees of hepatic steatosis were assessed for evidence of lipid peroxidation (malondialdehyde adducts), hepatic iron, inflammation, fibrosis, hepatic stellate cell activation (alpha-smooth muscle actin and TGF-beta expression) and collagen type I synthesis (procollagen alpha1 (I) mRNA).

RESULTS

Lipid peroxidation occurred in and adjacent to fat-laden hepatocytes and was maximal in acinar zone 3. Fibrosis was associated with steatosis (P < 0.04), lipid peroxidation (P < 0.05) and hepatic iron stores (P < 0.02). Multivariate logistic regression analysis confirmed the association between steatosis and lipid peroxidation within zone 3 hepatocytes (P < 0.05), while for hepatic iron, lipid peroxidation was seen within sinusoidal cells (P < 0.05), particularly in zone 1 (P < 0.02). Steatosis was also associated with acinar inflammation (P < 0.005). alpha-Smooth muscle actin expression was present in association with both lipid peroxidation and fibrosis. Although the effects of steatosis and iron on lipid peroxidation and fibrosis were additive, there was no evidence of a specific synergistic interaction between them.

CONCLUSIONS

These observations support a model where steatosis exerts an effect on fibrosis through lipid peroxidation, particularly in zone 3 hepatocytes.

Role of myofibroblasts in tumour encapsulation of hepatocellular carcinoma in haemochromatosis

BACKGROUND/AIMS

Hepatocellular carcinoma is a common malignancy and a major complication of untreated haemochromatosis. Encapsulation of liver tumours has been associated with a better prognosis and longer disease-free periods following resection. This study investigated the source of the tumour capsule in patients with haemochromatosis and coexisting hepatocellular carcinoma and examined potential factors influencing development.

METHODS

Five haemochromatosis patients with encapsulated hepatocellular carcinoma were studied. Myofibroblasts were identified using combined immunohistochemistry and in situ hybridisation for alpha-smooth muscle actin and procollagen alpha1(I) mRNA, respectively. Immunohistochemistry was also performed for transforming growth factor (TGF)-beta1, platelet-derived growth factor (PDGF)-beta receptor and malondialdehyde.

RESULTS

Procollagen alpha1(I) mRNA co-localised to alpha-smooth muscle actin positive myofibroblasts. The number of myofibroblasts was maximal within the capsule and decreased away from the tumour. TGF-beta1 protein was expressed in iron-loaded cells in non-tumour liver at the interface of tumour capsule. PDGF-beta receptor expression was observed in mesenchymal cells in the tumour capsule and in portal tracts. Malondialdehyde adducts were observed in the tumour, non-tumour tissue and in the capsule.

CONCLUSIONS

This study provides evidence that myofibroblasts are the cell type responsible for collagen production within the tumour capsule surrounding hepatocellular carcinoma in haemochromatosis. The production of TGF-beta1 by iron-loaded hepatic cells at the tumour capsule interface may perpetuate the myofibroblastic phenotype, resulting in the formation of the tumour capsule.

What's new in hemochromatosis

Hereditary hemochromatosis (HHC) is an inherited disorder of iron metabolism affecting approximately 1 in 200-300 individuals of Northern European descent. Over time, the continued deposition of iron in parenchymal cells of many organs can eventually lead to diabetes mellitus, cardiomyopathy, and hepatic cirrhosis, the last of which is frequently followed by hepatocellular carcinoma. Although the complications of HHC can be devastating, its clinical management is simple and effective if the disease is identified early in its progression. The recent elucidation of the HFE gene has provided insight into the pathogenesis of HHC and provided a means for the early identification of individuals in whom HHC may develop. Two mutations have been implicated in HHC: C282Y and H63D. The former occurs in a homozygous state seen in 75-100% of patients with HHC. The high correlation of HFE to HHC has caused it to be considered as a candidate gene for population-based genetic testing for diagnosis and detection of predisposition to HHC. In addition, mechanisms of iron transport and metabolism are unfolding and are providing clues to the enigma of iron homeostasis and the pathophysiology of iron overload.

Effect of hemochromatosis genotype and lifestyle factors on iron and red cell indices in a community population

BACKGROUND

Heterozygotes for the C282Y mutation of the HFE gene may have altered hematology indices and higher iron stores than wild-type subjects.

METHODS

We performed a cross-sectional analysis of 1488 females and 1522 males 20-79 years of age drawn from the Busselton (Australia) population study to assess the effects of HFE genotype, age, gender, and lifestyle on serum iron and hematology indices.

RESULTS

Male C282Y heterozygotes had increased transferrin saturation compared with the wild-type genotype. Neither male nor female heterozygotes had significantly increased ferritin values compared with the wild-type genotype. Younger (20-29 years) wild-type males, but not heterozygous males, had significantly lower ferritin values than wild-type males in the older age groups. Compound heterozygous subjects had increased means for serum iron, transferrin saturation, corpuscular volume, and corpuscular hemoglobin compared with the wild-type genotype, and the males also had increased ferritin values (medians 323 vs 177 microg/L; P = 0.003). In both male and female wild-type subjects, an increased body mass index was associated with decreased serum iron and transferrin saturation and increased ferritin values. There was a significant increase in ferritin concentrations in both genders with increasing frequency of red meat consumption above a baseline of 1-2 times per week and alcohol intakes >10 g/day.

CONCLUSIONS

Male C282Y heterozygotes had significantly increased transferrin saturation values. Compound heterozygous (C282Y/H63D) subjects formed a separate category of C282Y heterozygotes in whom both iron and red cell indices were significantly increased compared with the wild-type genotype.

Population screening for HFE-associated haemochromatosis: should we have to pay for our genes?

Haemochromatosis associated with mutations in the HFE gene is the most common inherited disorder in Caucasian populations. Early diagnosis and treatment allows for normal life expectancy, whereas there is considerable morbidity and early mortality in those patients diagnosed late or untreated. Unfortunately, the development of symptoms and signs in haemochromatosis is usually associated with significant iron overload. For this reason, many clinicians and geneticists have advocated population screening. The recent identification of the HFE gene and the availability of a simple DNA-based diagnostic test have led to international debate as to the most cost-effective means of population screening for HFE-associated haemochromatosis. The present paper summarizes the evidence in favour of population screening and analyses the relative advantages of genotypic (DNA test) versus phenotypic (transferrin saturation) testing.

Detection of male DNA in the liver of female patients with primary biliary cirrhosis

BACKGROUND/AIMS

Primary biliary cirrhosis is a chronic cholestatic liver disease characterized by progressive inflammatory destruction of bile ducts, with eventual hepatic fibrosis and cirrhosis. Since primary biliary cirrhosis affects predominantly middle-aged women and has pathological similarities to hepatic graft-versus-host-disease, we investigated whether fetal cell microchimerism might be involved in the development of this disease.

METHODS

The presence of Y-chromosome-specific sequences was analyzed by polymerase chain reaction using peripheral blood mononuclear cells from women with primary biliary cirrhosis (n=18) and healthy (control) women (n=18), and by in situ hybridization of liver biopsy sections from women with primary biliary cirrhosis (n=19) and women with chronic hepatitis C or alcoholic liver disease (n=20).

RESULTS

Male cells were detected in liver biopsy specimens of 8 of 19 patients (42%) with primary biliary cirrhosis. Y-chromosome-containing cells were not seen in any of the liver biopsy specimens from women with chronic hepatitis C or alcoholic liver disease. Male cells were detected in peripheral blood mononuclear cells from one healthy control at a level of 1 male cell per 10(6) female cells, but were not detected in peripheral blood mononuclear cells of women with primary biliary cirrhosis.

CONCLUSIONS

The presence of male cells in the liver of women with primary biliary cirrhosis raises the possibility that fetal cell microchimerism may be involved in the pathogenesis of this chronic liver disease.

Haemochromatosis in the new millennium

Hereditary haemochromatosis (HHC) is a common inherited disorder of iron metabolism characterised by progressive iron loading of parenchymal cells of the liver, pancreas, heart and other organs ultimately leading to cirrhosis and organ failure. Despite HLA studies which localised the defective gene to the short arm of chromosome 6, the haemochromatosis gene remained elusive until 1996, when the gene was identified by a massive positional cloning effort. The haemochromatosis gene (HFE) encodes a novel nonclassical MHC class-1-like molecule. Two missense mutations have been identified in patients with HHC, a G to A at nucleotide 845, resulting in a substitution of tyrosine for cysteine at amino acid 282 (referred to as the C282Y mutation) and a C to G at nucleotide 187, resulting in a substitution of aspartate for histidine at amino acid 63 (H63D). An average of 85-90% of patients with typical clinical features of HHC are homozygous for the C282Y mutation. H63D is not associated with the same degree of iron loading as C282Y. Clinical expression is variable depending on environmental (dietary) iron, physiological and pathological blood loss and as yet unidentified modifying genetic factors. One recent Australian study indicates that only about 50% of homozygous subjects are fully expressing and symptomatic and that about 30% show no clinical or biochemical expression. Genetic tests for identifying mutations in the HFE gene provide precise means for diagnosis, family testing and population screening and have led to re-evaluation of the indications for liver biopsy in this disease. At the present time, however, the most practical and cost-effective method of screening is for phenotypic expression by transferrin saturation or unsaturated iron binding capacity measurement. In the future, population screening by genotype should be feasible once the relevant technical, legal and ethical issues are resolved.

Effects of HFE C282Y and H63D polymorphisms and polygenic background on iron stores in a large community sample of twins

The aim of this study was to assess and to compare the role of HFE polymorphisms and other genetic factors in variation in iron stores. Blood samples were obtained from 3,375 adult male and female twins (age range 29-82 years) recruited from the Australian Twin Registry. There were 1,233 complete pairs (562 monozygotic and 571 dizygotic twins). Serum iron, transferrin, transferrin saturation with iron, and ferritin were measured, and the HFE C282Y and H63D genotypes were determined. The frequency of the C282Y allele was.072, and that of the H63D allele was.141. Significant sources of variation in the indices of iron status included age, sex, age-sex interaction, body-mass index, and both the C282Y and H63D genotypes. The iron, transferrin, and saturation values of CC and CY subjects differed significantly, but the ferritin values did not. After correction for age and body-mass index, 23% and 31% of the variance in iron, 66% and 49% of the variance in transferrin, 33% and 47% of the variance in transferrin saturation, and 47% and 47% of the variance in ferritin could be explained by additive genetic factors, for men and women, respectively. HFE C282Y and H63D variation accounted for <5% of the corrected phenotypic variance, except for saturation (12% in women and 5% in men). We conclude that HFE CY and HD heterozygotes differ in iron status from the CC and HH homozygotes and that serum transferrin saturation is more affected than is serum ferritin. There are highly significant effects of other as-yet-unidentified genes on iron stores, in addition to HFE genotype.

Automated measurement of unsaturated iron binding capacity is an effective screening strategy for C282Y homozygous haemochromatosis

BACKGROUND

C282Y hereditary haemochromatosis is an appropriate condition for population screening. Transferrin saturation, the best screening test to date, is relatively expensive, labour intensive, and cannot be automated. Unsaturated iron binding capacity is a surrogate marker of transferrin saturation and its measurement can be automated.

AIMS

To evaluate a screening strategy for C282Y hereditary haemochromatosis in a tertiary hospital environment based on unsaturated iron binding capacity as the initial screening test.

METHODS

Measurement of unsaturated iron binding capacity was adapted to the main laboratory analyser. An unsaturated iron binding capacity of less than 30 micromol/l was identified as an appropriate decision point and 5182 consecutive subjects were screened over 28 consecutive days.

RESULTS

Of those screened, 697 had an unsaturated iron binding capacity less than 30 micromol/l. Of these, transferrin saturation was greater than 40% in 294. A total of 227 were able to be genotyped for the C282Y mutation. Nine subjects homozygous for C282Y were identified. Based on full cost recovery, affected persons were identified at a cost of Aus$2268.77 per case (approximately US$1496).

CONCLUSION

Automated measurement of unsaturated iron binding capacity enables a cost effective, large scale population screening programme for C282Y hereditary haemochromatosis to be developed.

p73 is up-regulated in a subset of hepatocellular carcinomas

Loss of heterozygosity (LOH) at 1p36 occurs in a number of solid tumors including hepatocellular carcinoma (HCC). Recently, a novel gene, p73, has been identified at 1p36.33. p73 is structurally and functionally related to p53 located at 17p13.1, which is a target for inactivation in HCCs. p73 produces at least two splicing variants, p73alpha and beta, and a polymorphism in exon 2 results in two alleles, GC or AT. Initially, only the AT allele and p73alpha transcripts were identified in malignant cell lines, suggesting a role for these in the malignant phenotype. The aims of this study were to determine the extent of LOH at 1p36 and 17p13.1 in HCCs from Australia and South Africa, and to identify patterns of p73 mRNA and p73 and p53 protein expression. LOH at 1p36 was found in 8 of 25 Australian and 6 of 10 South African cases. p73 mRNA expression occurred in 8 HCCs, but not in nonmalignant liver tissue. Two of these 8 HCCs had LOH of 1p36. Both alpha and beta transcripts were observed in GC/GC homozygotes and GC/AT heterozygotes. No p73 protein expression was observed by immunohistochemistry in nonmalignant liver tissue or in HCC. p53 inactivation appeared to be associated with up-regulation of p73 expression, suggesting a compensatory role for p73 in this situation. The LOH at 1p36 implies a liver-specific tumor suppressor gene is in this region. However, the up-regulation of p73 mRNA suggests p73 is not the target of this loss.

Compound heterozygous hemochromatosis genotype predicts increased iron and erythrocyte indices in women

BACKGROUND

Women who inherit heterozygosity for the C282Y mutation of the HFE gene may have increased serum iron indices and hemoglobin and are less likely to develop iron deficiency compared with women with the wild-type genotype.

METHODS

We performed a cross-sectional analysis of 497 women 20-44 years of age and 830 women >51 years of age drawn from the Busselton (Australia) population study to assess the effects of the HFE genotype on serum iron and hematology indices.

RESULTS

Heterozygosity for the C282Y mutation occurred in 13.8% of the study population, comprising 11.8% C282Y wild-type heterozygotes and 2.0% C282Y/H63D compound heterozygotes. In the younger age group, C282Y wild-type women did not have significantly increased serum iron, transferrin saturation, or hemoglobin values, and were not protected from developing iron deficiency, compared with women of the same age with the wild-type genotype. Young compound heterozygous women had higher means for serum iron (25.0 vs 16.9 micromol/L; P <0.001), transferrin saturation (42.0% vs 25.6%; P <0. 05), hemoglobin (139.4 vs 132.3 g/L; P <0.05), and corpuscular volume (91.1 vs 87.7 fL; P <0.05), and a higher median ferritin (53 vs 44 microg/L; P <0.05) compared with the wild-type genotype. Similar results were observed for compound heterozygotes in the >51 years age group.

CONCLUSIONS

Women with the compound heterozygous HFE genotype C282Y/H63D, but not the C282Y wild-type genotype, had increased values for serum iron and transferrin saturation, and the younger age group also had increased hemoglobin values. We conclude that the compound heterozygous genotype may have a beneficial effect in protecting women from iron deficiency.

Hemochromatosis

The recent cloning of the hemochromatosis gene (HFE) and the demonstration that a single missense mutation is responsible for 90% or more of patients with the disease, have stimulated renewed interest in all aspects of this common disease. The molecular tests for identifying mutations in HFE provide improved means for diagnosis, family screening, and population screening. Moreover, the elucidation of the role of the HFE gene product will provide new insights into the regulation of normal iron absorption and iron metabolism. In addition, it is now apparent that iron, even in the modest tissue concentrations, can act as a co-factor in potentiating cell injury in other liver diseases.

HFE-associated hereditary hemochromatosis

Hereditary hemochromatosis is a common inherited disorder of the iron metabolism. Screening studies indicate that it has a prevalence of one in 200 to 400, depending on the population studied, and a carrier rate of about one in seven to one in 10. Feder et al identified the hereditary hemochromatosis gene (HFE) in 1996 and two candidate mutations; the C282Y mutation has been shown to be responsible for the majority of the hereditary hemochromatosis cases worldwide. The gene discovery has led to rapid advances in the field of iron metabolism. Although the basic defect is still not fully understood, much is known about the sequence of events leading to iron overload. Hereditary hemochromatosis is a major candidate for population screening and meets the screening criteria of the World Health Organization, and Wilson and Jungner. It is one of the most prevalent genetic diseases in white populations, and, importantly, early diagnosis and simple effective treatment allow normal life expectancy. The discovery of the HFE gene and the frequency of the single C282Y mutation as a cause of most cases of hereditary hemochromatosis allow the possibility of widespread genetic testing. However, the logistics, and the psychological and social consequence of this, coupled with incomplete expression of the genotype, necessitate further studies before population screening can be justified.

A population-based study of the clinical expression of the hemochromatosis gene

BACKGROUND AND METHODS

Hereditary hemochromatosis is associated with homozygosity for the C282Y mutation in the hemochromatosis (HFE) gene on chromosome 6, elevated serum transferrin saturation, and excess iron deposits throughout the body. To assess the prevalence and clinical expression of the HFE gene, we conducted a population-based study in Busselton, Australia. In 1994, we obtained blood samples for the determination of serum transferrin saturation and ferritin levels and the presence or absence of the C282Y mutation and the H63D mutation (which may contribute to increased hepatic iron levels) in 3011 unrelated white adults. We evaluated all subjects who had persistently elevated transferrin-saturation values (45 percent or higher) or were homozygous for the C282Y mutation. We recommended liver biopsy for subjects with serum ferritin levels of 300 ng per milliliter or higher. The subjects were followed for up to four years.

RESULTS

Sixteen of the subjects (0.5 percent) were homozygous for the C282Y mutation, and 424 (14.1 percent) were heterozygous. The serum transferrin saturation was 45 percent or higher in 15 of the 16 who were homozygous; in 1 subject it was 43 percent. Four of the homozygous subjects had previously been given a diagnosis of hemochromatosis, and 12 had not. Seven of these 12 patients had elevated serum ferritin levels in 1994; 6 of the 7 had further increases in 1998, and 1 had a decrease, although the value remained elevated. The serum ferritin levels in the four other homozygous patients remained in the normal range. Eleven of the 16 homozygous subjects underwent liver biopsy; 3 had hepatic fibrosis, and 1, who had a history of excessive alcohol consumption, had cirrhosis and mild microvesicular steatosis. Eight of the 16 homozygous subjects had clinical findings that were consistent with the presence of hereditary hemochromatosis, such as hepatomegaly, skin pigmentation, and arthritis.

CONCLUSIONS

In a population of white adults of northern European ancestry, 0.5 percent were homozygous for the C282Y mutation in the HFE gene. However, only half of those who were homozygous had clinical features of hemochromatosis, and one quarter had serum ferritin levels that remained normal over a four-year period.

The haemochromatosis gene: a global perspective and implications for the Asia-Pacific region

Mutations in the haemochromatosis (HFE) gene cause most of the cases of hereditary haemochromatosis among people of Northern European ancestry while remaining a rare cause of iron overload among indigenous persons of the Asia-Pacific region. Advances in understanding of the role of the HFE protein product and other recently cloned iron transporters signify an exciting period, as previously unknown components of the iron metabolism pathway are revealed one by one. Epidemiological studies have shown that this gene is more widespread than its phenotypic expression would suggest and that the heterozygous state may be implicated in the expression of other diseases of the liver such as porphyria cutanea tarda, hepatitis C virus infection and non-alcoholic steatohepatitis. The diagnosis, management and ethical implications for clinical practice in the aftermath of this discovery are discussed.

The haemochromatosis gene: a co-factor for chronic liver diseases?

There is increasing evidence that hepatotoxins, such as alcohol and the hepatitis viruses, act as co-factors in causing hepatic fibrosis and cirrhosis. For example, alcohol aggravates the hepatic damage produced by iron in hereditary haemochromatosis. We present evidence that the reverse is also true, that is, that iron loading of mild to moderate degree due to heterozygosity or homozygosity for the haemochromatosis genetic mutations acts as a significant hepatotoxin aggravating hepatic damage from other causes of liver disease. These include non-alcoholic steatohepatitis, chronic hepatitis C, porphyria cutanea tarda and possibly primary liver cell cancer. However, any additional hepatotoxic effect is due to the hepatic iron concentration and not the mutations in the haemochromatosis genes.

Linkage disequilibrium analysis in Australian haemochromatosis patients indicates bipartite association with clinical expression

BACKGROUND/AIMS

Hereditary haemochromatosis shows a wide variation in phenotypic expression, which is thought to be due, in part, to genetic factors. A single missense mutation in HFE, leading to an amino acid substitution (C282Y) has been shown to be the causative mutation, clearly responsible for clinical expression of the disorder. Since homozygosity for the C282Y mutation can give rise to a disorder which shows wide variation in clinical expression, we investigated the possibility that genetic modifiers of HFE may exist.

METHODS

Linkage disequilibrium analysis was performed on chromosome 6p21.3 in 74 patients homozygous for the C282Y mutation using microsatellite markers spanning the haemochromatosis gene region. Phenotypic expression was evaluated based on transferrin saturation, serum ferritin, hepatic iron concentration and index, and iron grade.

RESULTS

Linkage disequilibrium (LD) analysis showed a predominant ancestral haplotype from D6S265 to D6S2236 covering a region of approximately 5 Mb. The overall LD distribution in this region showed two peaks of highly significant association at D6S105 (2 Mb proximal to HFE) and at D6S2239 approximately 50 kb distal to HFE. Male patients homozygous for D6S105 allele 8, had significantly higher hepatic iron indices than patients heterozygous or nullizygous for D6S105-8 (p<0.038).

CONCLUSION

This analysis indicates that modifying gene(s) or another mutation affecting HHC clinical expression may be located in the region of D6S105.

Elevated serum type IV collagen: a sensitive indicator of the presence of cirrhosis in haemochromatosis

BACKGROUND/AIM

Hereditary haemochromatosis can now be diagnosed by genetic testing, although determining the presence or absence of cirrhosis remains crucial to patient management. While many studies have investigated the utility of various serum markers of cirrhosis in chronic liver diseases, few have examined specifically patients with hereditary haemochromatosis. The aim of this study was to assess the utility of serum type IV collagen and serum laminin in diagnosing hepatic fibrosis and cirrhosis in patients with hereditary haemochromatosis.

METHODS

The study group consisted of 42 patients with hereditary haemochromatosis and 19 Caucasian controls. Serum type IV collagen, laminin, matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase (TIMP-1) concentrations were measured by enzyme-linked immunosorbant assay in serum from patients with haemochromatosis and control subjects. Liver biopsies from patients with haemochromatosis were graded for fibrosis and correlated with serum markers of hepatic fibrosis.

RESULTS

Serum type IV collagen concentration was significantly increased in haemochromatosis patients compared to controls (130+/-79 ng/ml vs 81 +/- 17 ng/ml, p<0.05) and was significantly correlated with both the grade of histological fibrosis (r=0.67, p<0.0001) and serum MMP-2 levels (r=0.42, p<0.05). A serum type IV collagen concentration > 115 ng/ml (mean+2 SD of controls) was 100% sensitive and 69% specific in detecting severe (grade 3) fibrosis and cirrhosis. The sensitivity results of serum laminin and TIMP-1 were 11% and 56% respectively.

CONCLUSIONS

Elevated serum type IV collagen is a sensitive indicator of the presence of severe fibrosis and cirrhosis in patients with haemochromatosis. Useful markers of hepatic fibrosis in other chronic liver diseases may not be applicable to haemochromatosis.

Genetics of hemochromatosis

Hereditary hemochromatosis (HHC) is a common autosomal recessive disorder of iron metabolism that results in progressive iron overload and can be fatal if untreated. The hemochromatosis gene (HFE) was identified by positional cloning in 1996. Two missense mutations have been described in HFE. The majority of HHC patients are homozygous for a cysteine-to-tyrosine substitution (C282Y); however, a small number are homozygous for a histidine-to-aspartic-acid substitution (H63D) or are heterozygous for both of these mutations. Mechanisms by which C282Y and H63D may disrupt the normal functioning of HFE have been suggested, but the role of HFE in the process of normal iron metabolism has yet to be clearly defined.

Interrelationships of alcohol and iron in liver disease with particular reference to the iron-binding proteins, ferritin and transferrin

It is known that the regular consumption of alcohol is responsible for the disruption of normal iron metabolism in humans, resulting in the excess deposition of iron in the liver in approximately one-third of alcoholic subjects. The mechanisms involved are largely unknown; however, it is likely that the two major proteins of iron metabolism, ferritin and transferrin are intimately involved in the process. Tissue damage in alcoholic liver disease and the inherited iron-overload disease, haemochromatosis, are caused by excess alcohol and iron, respectively. The mechanisms of this damage are believed to be similar in both disease conditions and involve free radical-mediated toxicity. A high proportion of haemochromatosis sufferers consume excessive amounts of alcohol and synergistic hepatotoxic events may occur leading to the earlier development of liver cirrhosis. This review describes briefly the role of ferritin and transferrin in normal iron metabolism and in iron overload disease and explores the possible involvement of these proteins in the pathophysiology of excess iron deposition in alcoholic subjects.

Smoking, obesity, and hypertension alter the dose-response curve and test sensitivity of carbohydrate-deficient transferrin as a marker of alcohol intake

Serum carbohydrate-deficient transferrin (CDT) is a specific and comparatively sensitive marker of excessive alcohol use; however, reports of its sensitivity vary according to the population or patient groups studied and their average alcohol intake. We have characterized the dose-response curve between alcohol intake and CDT concentrations in a study of 1400 men and women from a community-based twin registry. Our results show that mean CDT increases with increasing reported alcohol consumption even within the range of alcohol use considered to be nonhazardous. We found significant effects of sex, age, smoking, previous alcohol dependence, body mass index, and diastolic hypertension on the alcohol-CDT dose-response curve. These variables either affect test sensitivity or require adjustment of reference intervals. The results also provide insight into the physiological and biochemical factors that affect CDT concentration.

Management of hemochromatosis. Hemochromatosis Management Working Group

The complications of iron overload in hemochromatosis can be avoided by early diagnosis and appropriate management. Therapeutic phlebotomy is used to remove excess iron and maintain low normal body iron stores, and it should be initiated in men with serum ferritin levels of 300 microg/L or more and in women with serum ferritin levels of 200 microg/L or more, regardless of the presence or absence of symptoms. Typically, therapeutic phlebotomy consists of 1) removal of 1 unit (450 to 500 mL) of blood weekly until the serum ferritin level is 10 to 20 microg/L and 2) maintenance of the serum ferritin level at 50 microg/L or less thereafter by periodic removal of blood. Hyperferritinemia attributable to iron overload is resolved by therapeutic phlebotomy. When applied before iron overload becomes severe, this treatment also prevents complications of iron overload, including hepatic cirrhosis, primary liver cancer, diabetes mellitus, hypogonadotrophic hypogonadism, joint disease, and cardiomyopathy. In patients with established iron overload disease, weakness, fatigue, increased hepatic enzyme concentrations, right upper quadrant pain, and hyperpigmentation are often substantially alleviated by therapeutic phlebotomy. Patients with liver disease, joint disease, diabetes mellitus and other endocrinopathic abnormalities, and cardiac abnormalities often require additional, specific management. Dietary management of hemochromatosis includes avoidance of medicinal iron, mineral supplements, excess vitamin C, and uncooked seafoods. This can reduce the rate of iron reaccumulation; reduce retention of nonferrous metals; and help reduce complications of liver disease, diabetes mellitus, and Vibrio infection. This comprehensive approach to the management of hemochromatosis can decrease the frequency and severity of iron overload, improve quality of life, and increase longevity.

Diagnosis of hemochromatosis

If untreated, hemochromatosis can cause serious illness and early death, but the disease is still substantially under-diagnosed. The cornerstone of screening and case detection is the measurement of serum transferrin saturation and the serum ferritin level. Once the diagnosis is suspected, physicians must use serum ferritin levels and hepatic iron stores on liver biopsy specimens to assess patients for the presence of iron overload. Liver biopsy is also used to establish the presence or absence of cirrhosis, which can affect prognosis and management. A DNA-based test for the HFE gene is commercially available, but its place in the diagnosis of hemochromatosis is still being evaluated. Currently, the most useful role for this test is in the detection of hemochromatosis in the family members of patients with a proven case of the disease. It is crucial to diagnose hemochromatosis before hepatic cirrhosis develops because phlebotomy therapy can avert serious chronic disease and can even lead to normal life expectancy.

Hereditary hemochromatosis: gene discovery and its implications for population-based screening

OBJECTIVE

To evaluate the role of genetic testing in screening for hereditary hemochromatosis to help guide clinicians, policymakers, and researchers.

PARTICIPANTS

An expert panel was convened on March 3, 1997, by the Centers for Disease Control and Prevention (CDC) and the National Human Genome Research Institute (NHGRI), with expertise in epidemiology, genetics, hepatology, iron overload disorders, molecular biology, public health, and the ethical, legal, and social implications surrounding the discovery and use of genetic information.

EVIDENCE

The group reviewed evidence regarding the clinical presentation, natural history, and genetics of hemochromatosis, including current data on the candidate gene for hemochromatosis (HFE) and on the ethical and health policy implications of genetic testing for this disorder.

CONSENSUS PROCESS

Consensus was achieved by group discussion confirmed by a voice vote. A draft of the consensus statement was prepared by a writing committee and subsequently reviewed and revised by all members of the expert group over a 1-year period.

CONCLUSIONS

Genetic testing is not recommended at this time in population-based screening for hereditary hemochromatosis, due to uncertainties about prevalence and penetrance of HFE mutations and the optimal care of asymptomatic people carrying HFE mutations. In addition, use of a genetic screening test raises concerns regarding possible stigmatization and discrimination. Tests for HFE mutations may play a role in confirming the diagnosis of hereditary hemochromatosis in persons with elevated serum iron measures, but even this use is limited by uncertainty about genotype-phenotype correlations. To address these questions, the expert group accorded high priority to population-based research to define the prevalence of HFE mutations, age and sex-related penetrance of different HFE genotypes, interactions between HFE genotypes and environmental modifiers, and psychosocial outcomes of genetic screening for hemochromatosis.

Haemochromatosis

Primary, hereditary or genetic haemochromatosis is one of the most common inherited disorders in a Caucasian populations with a disease frequency of 1:300-400 and a carrier frequency of approximately 10%. The basic genetic defect remains unknown, although the haemochromatosis gene has now been cloned and is known to be a member of the MHC non-classical class I family. Many factors--environmental, genetic and non-genetic in nature--influence the degree of iron loading in affected individuals. In particular, pathological and physiological blood loss influence iron stores in haemochromatosis. The iron concentration in the liver is an important determinant of survival because a hepatic iron concentration in excess of 400 mumol/g dry weight is usually associated with cirrhosis. Patients with cirrhosis secondary to haemochromatosis are at risk of hepatocellular carcinoma. The combination of improved awareness of the disease and the appropriate use of genetic testing for the common C282Y mutation should lead to earlier diagnosis and therapy.

Evidence for altered hepatic matrix degradation in genetic haemochromatosis

BACKGROUND

Altered matrix degradation contributes to fibrosis in some liver diseases but the role of matrix degradation in fibrogenesis associated with genetic haemochromatosis has not previously been addressed.

AIMS

To measure serum concentrations of tissue inhibitor of metalloproteinase 1 (TIMP-1) and matrix metalloproteinases (MMP), MMP-1, MMP-2, and MMP-3 in patients with haemochromatosis and control subjects.

PATIENTS

Forty patients with haemochromatosis and 19 healthy control subjects. Ten of the 40 patients were studied before and after venesection therapy.

METHODS

Serum levels of TIMP-1, MMP-1, MMP-2, and MMP-3 were measured by enzyme immunoassay and correlated to hepatic iron concentration and degree of histological fibrosis.

RESULTS

Serum TIMP-1 was increased in patients with haemochromatosis compared with controls (163 (30) versus 123 (28) ng/ml, p < 0.0002). Mean serum TIMP-1 concentration of patients with haemochromatosis without fibrosis was significantly higher than in controls (153 (16) versus 123 (28) ng/ml, p = 0.03). Serum TIMP-1 concentration correlated with both hepatic iron concentration and hepatic iron index (r = 0.42, p < 0.01; r = 0.42, p < 0.01). Serum MMP-2 concentrations correlated with increasing degree of fibrosis in patients with haemochromatosis (r = 0.38, p = 0.01). The mean MMP-1: TIMP-1, MMP-2:TIMP-1 and age/sex matched MMP-3:TIMP-1 ratios were significantly lower in patients with haemochromatosis than controls (0.11 (0.06) versus 0.2 (0.14), p = 0.02; 3.32 (0.9) versus 3.91 (0.81), p = 0.05; and 0.26 (0.12) versus 0.47 (0.27), p = 0.007, respectively). Following venesection, MMP-2 and MMP-3 concentrations increased by 11% (p = 0.03) and 19% (p = 0.03), respectively.

CONCLUSIONS

This study provides the first evidence of an alteration in matrix degradation in haemochromatosis that may be a contributing factor to hepatic fibrogenesis in this disease.

Expression of HLA-linked hemochromatosis in subjects homozygous or heterozygous for the C282Y mutation

BACKGROUND & AIMS

In the absence of a genetic test, diagnostic criteria for hereditary hemochromatosis have been imprecise. The identification of the HFE gene and the C282Y mutation allow definition of expression of this disease and reassessment of diagnostic criteria. The aim of this study was to analyze the concordance between the genetic diagnosis and the previous clinical diagnosis in families with hemochromatosis.

METHODS

Three hundred subjects were tested for the C282Y mutation and were grouped as homozygous, heterozygous, or homozygous normal.

RESULTS

All adults previously diagnosed as homozygous or heterozygous for HLA-linked hereditary hemochromatosis carried at least one C282Y mutation. Two adolescents, previously thought to be homozygous, had no C282Y mutation. Of 127 subjects homozygous for the mutation, 105 met criteria for diagnosis. Iron overload was not expressed in 6.7% of homozygous men and 32.7% of homozygous women. The iron indices in 8 of 171 subjects heterozygous for the C282Y mutation were within the range previously regarded as indicative of homozygosity. Seven of these 8 carried the H63D mutation.

CONCLUSIONS

In Australia, 17.3% of subjects homozygous for the C282Y mutation do not express iron overload to meet current diagnostic criteria of hemochromatosis. In subjects heterozygous for the mutation, 4.8% have iron overload in the range previously diagnosed as homozygous. Nonexpression is common, particularly in women.

Effect of long-term corticosteroid therapy on monocyte chemotaxis in man

The influence of prednisolone on monocyte chemotactic activity in vitro at prednisolone concentrations comparable with those achieved in man following oral dosage has been investigated. Chemotactic activity of monocytes from each of sixteen normal subjects was suppressed by concentrations of prednisolone as low as 25 ng/ml (suppression of chemotaxis, 20%). Maximal suppression occurred at 100 ng/ml (suppression of chemotaxis, 48%) and no significant increase in suppression was produced by increasing the concentration to 200 ng/ml (suppression of chemotaxis, 53%). In contrast, monocytes isolated from ten patients receiving corticosteroid therapy showed no significant suppression of chemotactic activity when exposed to these concentrations of prednisolone, even though they exhibited a normal ability to respond to a chemotactic stimulus. The lack of suppression of monocyte chemotaxis in patients receiving corticosteroid therapy is unexplained, but may represent a change in the circulating monocyte or lymphocyte populations.

The spinal muscular atrophy gene region at 5q13.1 has a paralogous chromosomal region at 6p21.3

Paralogous regions are duplicated segments of chromosomal DNA that have been acquired during the evolution of the genome. Subsequent divergent evolution of the genes within paralogous regions can lead to the formation of gene families. Here, we report the identification of a region on Chromosome (Chr) 6 at 6p21.3 that is paralogous with the Spinal Muscular Atrophy (SMA) gene region on Chr 5 at 5q13.1. Partial characterization of this region identified nine sequences all of which are highly homologous to DNA sequences of the SMA gene region at 5q13.1. These sequences include four beta-glucuronidase sequences, two retrotransposon sequences, a novel cDNA, a Sequence Tagged Site (STS), and one that is homologous to exon 9 of the Neuronal Apoptosis Inhibitor Protein (NAIP) gene. The 6p21.3 paralogous SMA region may contain genes that are related to those in the SMA region at 5q13.1; however, a direct association of this region with SMA is unlikely given that no linkage of SMA with Chr 6 has been reported.

Distribution of transferrin saturation in an Australian population: relevance to the early diagnosis of hemochromatosis

BACKGROUND & AIMS

An elevated transferrin saturation is the earliest phenotypic abnormality in hereditary hemochromatosis. Determination of transferrin saturation remains the most useful noninvasive screening test for affected individuals, but there is debate as to the appropriate screening level. The aims of this study were to estimate the mean transferrin saturation in hemochromatosis heterozygotes and normal individuals and to evaluate potential transferrin saturation screening levels.

METHODS

Statistical mixture modeling was applied to data from a survey of asymptomatic Australians to estimate the mean transferrin saturation in hemochromatosis heterozygotes and normal individuals. To evaluate potential transferrin saturation screening levels, modeling results were compared with data from identified hemochromatosis heterozygotes and homozygotes.

RESULTS

After removal of hemochromatosis homozygotes, two populations of transferrin saturation were identified in asymptomatic Australians (P < 0.01). In men, 88.2% of the truncated sample had a lower mean transferrin saturation of 24.1%, whereas 11.8% had an increased mean transferrin saturation of 37.3%. Similar results were found in women. A transferrin saturation threshold of 45% identified 98% of homozygotes without misidentifying any normal individuals.

CONCLUSIONS

The results confirm that hemochromatosis heterozygotes form a distinct transferrin saturation subpopulation and support the use of transferrin saturation as an inexpensive screening test for hemochromatosis. In practice, a fasting transferrin saturation of > or = 45% identifies virtually all affected homozygous subjects without necessitating further investigation of unaffected normal individuals.