Hemochromatosis in Italy in the last 30 years: role of genetic and acquired factors

HIF1A: A Putative Modifier of Hemochromatosis

HFE-related hereditary hemochromatosis (HH) is characterized by marked phenotypic heterogeneity. Homozygosity for p.C282Y is a low penetrance genotype suggesting that the HFE-HH is a multifactorial disease resulting from a complex interaction involving a major gene defect, genetic background and environmental factors. We performed a targeted NGS-based gene panel to identify new candidate modifiers by using an extreme phenotype sampling study based on serum ferritin and iron removed/age ratio. We found an increased prevalence of the HIF1A p.Phe582Ser and p.Ala588Thr variants in patients with a severe iron and clinical phenotype. Accordingly, Huh-7 cells transfected with both variants showed significantly lower HAMP promoter activity by luciferase assay. The qRT-PCR assays showed a downregulation of hepcidin and an upregulation of the HIF1A target genes (VEGF, HMOX, FUR, TMPRSS6) in cells transfected with the HIF1A-P582S vector. We identified mutations in other genes (e.g., Serpina1) that might have some relevance in single cases in aggravating or mitigating disease manifestation. In conclusion, the present study identified HIF1A as a possible modifier of the HFE-HH phenotype cooperating with the genetic defect in downregulating hepcidin synthesis. In addition, this study highlights that an NGS-based approach could broaden our knowledge and help in characterizing the genetic complexity of HFE-HH patients with a severe phenotype expression.

Prevalence and characteristics of anti-HCV positivity and chronic hepatitis C virus infection in HFE p.C282Y homozygotes

INTRODUCTION AND AIM

Observations of hepatitis C virus (HCV) infection in adults with hemochromatosis are limited.

MATERIALS AND METHODS

We determined associations of serum ferritin (SF) with anti-HCV in non-Hispanic white North American adults in a post-screening examination. Cases included p.C282Y homozygotes (regardless of screening transferrin saturation (TS) and SF) and participants (regardless of HFE genotype) with high screening TS/SF. Controls included participants without p.C282Y or p.H63D who had normal screening TS/SF. Participants with elevated alanine aminotransferase underwent anti-HCV testing. We determined prevalence of chronic HCV infection in consecutive Alabama and Ontario referred adults with HFE p.C282Y homozygosity.

RESULTS

In post-screening participants, anti-HCV prevalence was 0.3% [95% CI: 0.02, 2.2] in 294 p.C282Y homozygotes, 9.5% [7.2, 12.3] in 560 Cases without p.C282Y homozygosity, and 0.7% [0.2, 2.3] in 403 Controls. Anti-HCV was detected in 7.2% of 745 participants with and 0.8% of 512 participants without elevated SF (odds ratio 9.9 [3.6, 27.6]; p<0.0001). Chronic HCV infection prevalence in 961 referred patients was 1.0% (10/961) [95% confidence interval (CI): 0.5, 2.0]. Ten patients with chronic HCV infection had median age 45y (range 29-67) and median SF 1163μg/L (range 303-2001). Five of eight (62.5%) patients had biopsy-proven cirrhosis.

CONCLUSIONS

Odds ratio of anti-HCV was increased in post-screening participants with elevated SF. Prevalence of anti-HCV in post-screening participants with HFE p.C282Y homozygosity and chronic HCV infection in referred adults with HFE p.C282Y homozygosity in North America is similar to that of Control participants with HFE wt/wt and normal screening TS/SF.

Inherited iron overload disorders

Hereditary iron overload includes several disorders characterized by iron accumulation in tissues, organs, or even single cells or subcellular compartments. They are determined by mutations in genes directly involved in hepcidin regulation, cellular iron uptake, management and export, iron transport and storage. Systemic forms are characterized by increased serum ferritin with or without high transferrin saturation, and with or without functional iron deficient anemia. Hemochromatosis includes five different genetic forms all characterized by high transferrin saturation and serum ferritin, but with different penetrance and expression. Mutations in HFE, HFE2, HAMP and TFR2 lead to inadequate or severely reduced hepcidin synthesis that, in turn, induces increased intestinal iron absorption and macrophage iron release leading to tissue iron overload. The severity of hepcidin down-regulation defines the severity of iron overload and clinical complications. Hemochromatosis type 4 is caused by dominant gain-of-function mutations of ferroportin preventing hepcidin-ferroportin binding and leading to hepcidin resistance. Ferroportin disease is due to loss-of-function mutation of SLC40A1 that impairs the iron export efficiency of ferroportin, causes iron retention in reticuloendothelial cell and hyperferritinemia with normal transferrin saturation. Aceruloplasminemia is caused by defective iron release from storage and lead to mild microcytic anemia, low serum iron, and iron retention in several organs including the brain, causing severe neurological manifestations. Atransferrinemia and DMT1 deficiency are characterized by iron deficient erythropoiesis, severe microcytic anemia with high transferrin saturation and parenchymal iron overload due to secondary hepcidin suppression. Diagnosis of the different forms of hereditary iron overload disorders involves a sequential strategy that combines clinical, imaging, biochemical, and genetic data. Management of iron overload relies on two main therapies: blood removal and iron chelators. Specific therapeutic options are indicated in patients with atransferrinemia, DMT1 deficiency and aceruloplasminemia.

Impact of natural neuromedin-B receptor variants on iron metabolism

Iron overload heritability remains partly unexplained. By performing whole exome sequencing in three patients with a clinical phenotype of hemochromatosis not accounted by known genetic risk factors, we identified in all patients rare variants predicted to alter activity of Neuromedin-B receptor (NMBR). Coding NMBR mutations were enriched in 129 patients with hereditary hemochromatosis or iron overload phenotype, as compared to ethnically matched controls, including 100 local healthy blood donors and 1000Genomes project participants (15.5% vs 5%, P = .0038 at burden test), and were associated with higher transferrin saturation in regular blood donors (P = .04). Consistently, in 191 patients with nonalcoholic fatty liver, the most common low-frequency p.L390 M variant was independently associated with higher ferritin (P = .03). In 58 individuals, who underwent oral iron challenge, carriage of the p.L390 M variant was associated with higher transferrin saturation and lower hepcidin release. Furthermore, the circulating concentration of the natural NMBR ligand, Neuromedin-B, was reduced in response to iron challenge. It was also decreased in individuals carrying the p.L390 M variant and with hemochromatosis in parallel with increased transferrin saturation. In mice, Nmbr was induced by chronic dietary iron overload in the liver, gut, pancreas, spleen, and skeletal muscle, while Nmb was downregulated in gut, pancreas and spleen. Finally, Nmb amplified holo-transferrin dependent induction of hepcidin in primary mouse hepatocytes, which was associated with Jak2 induction and abolished by the NMBR antagonist PD168368. In conclusion, NMBR natural variants were enriched in patients with iron overload, and associated with facilitated iron absorption, possibly related to a defect of iron-induced hepcidin release.

Modern Outcomes Following Treatment of Hepatocellular Carcinoma in Hereditary Hemochromatosis: A Matched Cohort Study

OBJECTIVE

Hepatocellular carcinoma (HCC) is a complication of the common genetic condition hereditary hemochromatosis (HH). It is unknown whether HH as an etiology of liver disease impacts the outcome. We compared the results of liver transplantation (LT), surgical resection and locoregional therapies in a matched cohort study and investigated whether HH as an etiology has an impact on survival.

MATERIALS AND METHODS

Consecutive patients with HH and HCC (2000 to 2015) were compared with age, sex and Barcelona Clinic Liver Cancer (BCLC) stage-matched non-HH HCC cases. Patients were offered curative or noncurative treatment according to BCLC stage and Milan criteria. The primary endpoint was all-cause mortality.

RESULTS

A total of 102 patients (52 HH; total cohort median age: 67 [44 to 78] y, 97% male, Model for End-stage Liver Disease: 9 [5 to 31]) were studied with a median follow-up of 22 (3 to 126) months. Of the HH cases, the median serum ferritin at diagnosis of HCC was 326 (27 to 5718) μg/L and α-fetoprotein 33 (2 to 197,926) kIU/L. Five-year survival for HH patients receiving curative therapy was 77% (80% for LT, 67% for resection/radiofrequency ablation), and 15% (23% for transarterial chemoembolization) for those undergoing noncurative therapy. Survival for HH patients compared with controls was similar (hazard ratio=0.949; P=0.839). On multivariate Cox regression survival analysis, BCLC stage, and diagnosis of ischemic heart disease (but not HH diagnosis) were independently associated with reduced survival.

CONCLUSIONS

Patients with HCC and HH can achieve comparable survival rates following curative or LRT modalities to other liver diseases. The BCLC staging system accurately stratifies survival and excellent 5-year survival is possible following LT in selected patients.

Reduced phenotypic expression in genetic hemochromatosis with time: Role of exposure to non-genetic modifiers

BACKGROUND & AIMS

Genetic hemochromatosis is mainly related to the homozygous p.Cys282Tyr (C282Y) mutation in the HFE gene, which causes hepcidin deficiency. Its low penetrance suggests the involvement of cofactors that modulate its expression. We aimed to describe the evolution of disease presentation and of non-genetic factors liable to impact hepcidin production in the long term.

METHODS

Clinical symptoms, markers of iron load, and risk factors according to the year of diagnosis were recorded over 30 years in a cohort of adult C282Y homozygotes. A total of 2,050 patients (1,460 probands [804 males and 656 females] and 542 relatives [244 males and 346 females]) were studied.

RESULTS

Over time: (i) the proband-to-relative ratio remained roughly stable; (ii) the gender ratio tended towards equilibrium among probands; (iii) age at diagnosis did not change among males and increased among females; (iv) the frequency of diabetes and hepatic fibrosis steadily decreased while that of chronic fatigue and distal joint symptoms remained stable; (v) transferrin saturation, serum ferritin and the amount of iron removed decreased; and (vi) the prevalence of excessive alcohol consumption decreased while that of patients who were overweight increased. Tobacco smoking was associated with increased transferrin saturation.

CONCLUSION

Genetic testing did not alter the age at diagnosis, which contrasts with the dramatic decrease in iron load in both genders. Tobacco smoking could be involved in the extent of iron loading. Besides HFE testing, which enables the diagnosis of minor forms of the disease, the reduction of alcohol consumption and the increased frequency of overweight patients may have played a role in the decreased long-term iron load, as these factors are likely to improve hepcidin production.

LAY SUMMARY

Genetic hemochromatosis is an inherited disorder that leads to progressive iron overload in the body. It results in chronic fatigue and in potential liver (cirrhosis), pancreas (diabetes) and joint (arthritis) damage in adulthood. The present study showed that tobacco smoking may aggravate iron loading, but that hemochromatosis has become less and less severe over the last 30 years despite patients being older at diagnosis, likely because of the protective effects of lower alcohol consumption and of increased weight in the French population.

Haemochromatosis

Haemochromatosis is now known to be an iron-storage disease with genetic heterogeneity but with a final common metabolic pathway resulting in inappropriately low production of the hormone hepcidin. This leads to increase in intestinal absorption and deposition of excessive amounts of iron in parenchymal cells which in turn results in eventual tissue damage and organ failure. A clinical enigma has been the variable clinical expression with some patients presenting with hepatic cirrhosis at a young age and others almost asymptomatic for life. Research is unravelling this puzzle by identifying environmental factors-especially alcohol consumption-and associated modifying genes that modulate phenotypic expression. A high index of suspicion is required for early diagnosis but this can lead to presymptomatic therapy and a normal life expectancy. Venesection (phlebotomy) therapy remains the mainstay of therapy, but alternative therapies are the subject of current research.

Endocrine dysfunction in hereditary hemochromatosis

Hereditary hemochromatosis (HH) is a genetic disorder of iron overload and subsequent organ damage. Five types of HH are known, classified by age of onset, genetic cause, clinical manifestations and mode of inheritance. Except for the rare form of juvenile haemochromatosis, symptoms do not usually appear until after decades of progressive iron loading and may be triggered by environmental and lifestyle factors. Despite the last decades discovery of genetic and phenotype diversity of HH, early studies showed a frequent involvement of the endocrine glands where diabetes and hypogonadism are the most common encountered endocrinopathies. The pathogenesis of diabetes is still relatively unclear, but the main mechanisms include the loss of insulin secretory capacity and insulin resistance secondary to liver damage. The presence of obesity and/or genetic predisposition may represent addictive risk factor for the development of this metabolic disease. Although old cases of primary gonad involvement are described, hypogonadism is mainly secondary to selective deposition of iron on the gonadotropin-producing cells of the pituitary gland, leading to hormonal impaired secretion. Cases of hypopituitarism or selected tropin defects, and abnormalities of adrenal, thyroid and parathyroid glands, even if rare, are reported. The prevalence of individual gland dysfunction varies enormously within studies for several bias due to small numbers of and selected cases analyzed, mixed genotypes and missing data on medical history. Moreover, in the last few years early screening and awareness of the disease among physicians have allowed hemochromatosis to be diagnosed in most cases at early stages when patients have no symptoms. Therefore, the clinical presentation of this disease has changed significantly and the recognized common complications are encountered less frequently. This review summarizes the current knowledge on HH-associated endocrinopathies.

Proprotein convertase 7 rs236918 associated with liver fibrosis in Italian patients with HFE-related hemochromatosis

BACKGROUND AND AIM

p.Cys282Tyr homozygosity is the prevalent genotype in (HFE)-related Hereditary Hemochromatosis with low penetrance and variable expression. However, liver cirrhosis and hepatocellular carcinoma remain the main causes of mortality in these patients. Detection of genetic modifiers identifying patients at risk for liver damage would be relevant for their clinical management. We evaluated proprotein convertase 7 (PCSK7) rs236918 as genetic marker of risk of liver fibrosis in an Italian cohort of p.Cys282Tyr homozygotes.

METHODS

Liver fibrosis was histologically assessed by Ishak score. We evaluated PCSK7 alleles and genotypes frequencies according to single or grouped staging scores: absent/mild fibrosis (stage: 0-2), moderate (stage: 3-4), and severe fibrosis/cirrhosis (stage: 5-6). Single nucleotide polymorphism genotyping was performed by restriction fragment length polymorphism or Taqman 5'-nuclease assays.

RESULTS

The rs236918 allele C frequency increased from stages 0-2 to 5-6 (7.1% vs 13.6%, vs 21.9%, P = 0.003). The wild-type genotype was significantly more frequent in the absent/mild fibrosis group (54.2%) compared with only 17% in patients with severe fibrosis/cirrhosis. At univariate proportional odds model, patients with GC + CC genotypes were 2.77 times (P = 0.0018) more likely to have worse liver staging scores than wild-type patients. In the adjusted analysis, odds ratio was 2.37 (P = 0.0218), and 2.56 (P = 0.0233) when the analysis was restricted to males. An exploratory mediation analysis suggested a direct effect of genotype on severe fibrosis/cirrhosis (odds ratio = 3.11, P = 0.0157), and a mild non-significant indirect effect mediated through iron accounting for 28%.

CONCLUSIONS

These findings confirm that PCSK7 rs236918 C allele is a risk factor for cirrhosis development in Italian patients with HFE-Hemochromatosis.

Management of human factors engineering-associated hemochromatosis: A 2015 update

This review focuses on the management of iron metabolism and iron overload experienced in the hereditary condition, human factors engineering (HFE)-associated hemochromatosis. Hemochromatosis refers to a group of genetic diseases that result in iron overload; the major one globally is HFE-associated hemochromatosis. The evolution in understanding of the most common form of hereditary hemochromatosis, being the substation of cysteine to a tyrosine at position 282 in the HFE gene, has been extensively studied Novel mutations in both HFE and non-HFE genes have been indicated in this disease which hold significance in its application for the Asia-Pacific region. In conditions with iron overload, the storage of excess iron in various body tissues leads to complications and toxic damage. The most common presenting complaint for this disease is malaise, lethargy and other non-specific symptoms. In order to diagnose hereditary hemochromatosis, there are biochemical, imaging and genetic testing options. Currently, cascade screening of affected families is preferred over population-level screening. The mainstay of treatment is venesection and the appropriate approach to treatment has been consolidated over the years. Recently, the indications for venesection therapy of hemochromatosis have been challenged and are the subject of ongoing research.

Significant Association Between Adiponutrin and Hepatocellular Carcinoma Risk

ADPN I148M polymorphism has been consistently reported to play a role in liver-associated diseases, such as alcoholic liver disease, chronic hepatitis C, and liver fat and fibrosis in nonalcoholic fatty liver disease. This significant association was also indicated in a series of hepatocellular carcinoma (HCC) studies, where the significance may be affected due to the small sample sizes. The aim of this study was to reexamine the ADPN-HCC association by use of meta-analysis. Biweekly computer-based literature searches plus manual screening were undertaken in an effort to identify all studies that met the predefined inclusion criteria. The Mantel-Haenszel method was selected to estimate risk effects (odds ratio [OR] and 95% confidence interval [CI]). To examine reliability of the pooled risk effects, we additionally performed sensitivity analysis and publication bias tests. Ten studies (1335 HCC patients and 2927 HCC-free controls) were identified for the meta-analysis. We found significantly increased risk of HCC attributable to presence of ADPN I148M polymorphism, with the highest risk associated with the M/M genotype under the recessive model of inheritance (OR = 2.23, 95% CI = 1.87-2.67, between-study heterogeneity: P = 0.468). The significant increase persisted in Caucasian and African when data were stratified by ethnicity. Subgroup analysis according to source of controls revealed similar risk effects. Our meta-analysis indicates that I148M polymorphism in the ADPN gene may independently contribute to the progression of HCC irrespective of the etiologies.

Non-invasive assessment of liver fibrosis in C282Y homozygous HFE hemochromatosis

BACKGROUND & AIMS

C282Y homozygotes with serum ferritin (SF) levels >1000 μg/L and/or increased serum transaminase levels are at risk of severe F3/F4 fibrosis. Current practical guidelines recommend liver biopsy in such individuals. This prospective observational cohort study aimed to evaluate non-invasive alternative means such as hyaluronic acid (HA) and transient elastography (TE) for the assessment of severe fibrosis in patients with SF >1000 μg/L or elevated transaminases.

METHODS

Between September 2005 and April 2013, 77 patients diagnosed C282Y homozygotes underwent a liver biopsy because of SF >1000 μg/L and/or increased transaminases according to current guidelines, with concomitant TE. All of them had clinical and biological evaluation, including HA measurement in 52 cases.

RESULTS

A total of 19.5% of patients had F3-F4 severe fibrosis. HA was higher in patients with severe fibrosis, but did not accurately predict severe fibrosis. TE was significantly higher in patients with severe fibrosis (17.2 vs. 4.9 kPa; P < 0.05) and was able to accurately predict fibrosis stage in 47/61 (77%) patients with valid measurement using a lower threshold of 6.4 kPa and an upper threshold of 13.9 kPa. Efficient assessment of severe fibrosis was not possible in patients with intermediate TE values.

CONCLUSION

An algorithm that successively employed SF and TE can accurately classify severe fibrosis in 61% of patients, restricting the need for liver biopsy to the 39% of patients with intermediate or unvalid TE values. This algorithm should be validated in independent cohorts before extended use.

Recent advances in hemochromatosis: a 2015 update : a summary of proceedings of the 2014 conference held under the auspices of Hemochromatosis Australia

This review focuses on iron metabolism, the genetics of hemochromatosis, current treatment protocols and various screening methods. Even though the most common form of hereditary hemochromatosis, C282Y gene mutations in the HFE gene, has been extensively studied, novel mutations in both HFE and non-HFE genes have been implicated in this disease. These have important implications for the Asia-Pacific region. In overload, deposition of iron in various body tissues leads to toxic damage. Patients commonly present with non-specific symptoms of malaise and lethargy. Biochemical, imaging and genetic testing can be carried out to confirm diagnosis. Venesection forms the mainstay of treatment and at present cascade screening of affected families is recommended over population-level screening.

Decreased cardiovascular and extrahepatic cancer-related mortality in treated patients with mild HFE hemochromatosis

BACKGROUND & AIMS

Mortality studies in patients with hemochromatosis give conflicting results especially with respect to extrahepatic causes of death. Our objective was to assess mortality and causes of death in a cohort of patients homozygous for the C282Y mutation in the HFE gene, diagnosed since the availability of HFE testing.

METHODS

We studied 1085 C282Y homozygotes, consecutively diagnosed from 1996 to 2009, and treated according to current recommendations. Mortality and causes of death were obtained from death certificates and compared to those of the general population. Standardized mortality ratios (SMRs) were used to assess specific causes of death and the Cox model was used to identify prognostic factors for death.

RESULTS

Patients were followed for 8.3±3.9 years. Overall the SMR was the same as in the general population (0.94 CI: 0.71-1.22). Patients with serum ferritin⩾2000 μg/L had increased liver-related deaths (SMR: 23.9 CI: 13.9-38.2), especially due to hepatic cancer (SMR: 49.1 CI: 24.5-87.9). Patients with serum ferritin between normal and 1000 μg/L had a lower mortality than the general population (SMR: 0.27 CI: 0.1-0.5), due to a decreased mortality, related to reduced cardiovascular events and extrahepatic cancers in the absence of increased liver-related mortality. Age, diabetes, alcohol consumption, and hepatic fibrosis were independent prognostic factors of death.

CONCLUSIONS

In treated HFE hemochromatosis, only patients with serum ferritin higher than 2000 μg/L have an increased mortality, mainly related to liver diseases. Those with mild iron burden have a decreased overall mortality in relation to reduced cardiovascular and extrahepatic cancer-related events. These results support a beneficial effect of early and sustained management of patients with iron excess, even when mild.

Metabolic alterations, HFE gene mutations and atherogenic lipoprotein modifications in patients with primary iron overload

HFE gene mutations contributed to a decrease of insulin secretion, an atherogenic LDL subfraction distribution and altered LDL and HDL particles in patients with iron overload. It remains to be determined whether these alterations contribute to cardiovascular risk.

Hepatocellular carcinoma in nonalcoholic fatty liver: Role of environmental and genetic factors

Hepatocellular carcinoma (HCC) is the fourth cause of cancer related mortality, and its incidence is rapidly increasing. Viral hepatitis, alcohol abuse, and exposure to hepatotoxins are major risk factors, but nonalcoholic fatty liver disease (NAFLD) associated with obesity, insulin resistance, and type 2 diabetes, is an increasingly recognized trigger, especially in developed countries. Older age, severity of insulin resistance and diabetes, and iron overload have been reported to predispose to HCC in this context. Remarkably, HCCs have been reported in non-cirrhotic livers in a higher proportion of cases in NAFLD patients than in other etiologies. Inherited factors have also been implicated to explain the different individual susceptibility to develop HCC, and their role seems magnified in fatty liver, where only a minority of affected subjects progresses to cancer. In particular, the common I148M variant of the PNPLA3 gene influencing hepatic lipid metabolism influences HCC risk independently of its effect on the progression of liver fibrosis. Recently, rare loss-of-function mutations in Apolipoprotein B resulting in very low density lipoproteins hepatic retention and in Telomerase reverse transcriptase influencing cellular senescence have also been linked to HCC in NAFLD. Indeed, hepatic stellate cells senescence has been suggested to bridge tissue aging with alterations of the intestinal microbiota in the pathogenesis of obesity-related HCC. A deeper understanding of the mechanisms mediating hepatic carcinogenesis during insulin resistance, and the identification of its genetic determinants will hopefully provide new diagnostic and therapeutic tools.

Hepatic iron overload and hepatocellular carcinoma

In recent years it has become increasingly evident that excess body iron may be complicated by the supervention of hepatocellular carcinoma (HCC). Hereditary hemochromatosis (HH) was the first condition in which hepatic iron overload was shown to predispose to the development of HCC. The inherited predisposition to excessive absorption of dietary iron in HH is almost always the result of homozygosity of the C282Y mutation of the HFE gene, which causes inappropriately low secretion of hepcidin. HCC develops in 8-10% of patients with HH and is responsible for approximately 45% of deaths in the HCC patients. Cirrhosis is almost always present when HCC is diagnosed. Dietary iron overload is a condition which occurs in rural-dwelling Black Africans in southern Africa as a result of the consumption, over time, of large volumes of alcohol home-brewed in iron containers and having, as a consequence, a high iron content. Iron loading of the liver results and may be complicated by malignant transformation of the liver (relative risk of approximately 10.0). Accompanying cirrhosis does occur but is less common than that in HH. The development of HCC as a consequence of increased dietary iron, and the fact that it may develop in the absence of cirrhosis, has been confirmed in an animal model. Drinking water with a high iron content might contribute to the high incidence of HCC in parts of Taiwan. The metabolic syndrome [obesity, insulin resistance type 2 (or diabetes mellitus type 2), non-alcoholic fatty liver or non-alcoholic steatohepatitis] has in recent years become a major public health problem in some resource-rich countries. A link between excess body iron and insulin resistance or the metabolic syndrome has become apparent. The metabolic syndrome may be complicated by the supervention of HCC, and recent evidence suggests that increased body iron may contribute to this complication.

Liver transplantation normalizes serum hepcidin level and cures iron metabolism alterations in HFE hemochromatosis

Defects in human hemochromatosis protein (HFE) cause iron overload due to reduced hepatic hepcidin secretion. Liver transplantation (LT) is a key treatment for potential complications from HFE-related hereditary hemochromatosis (HH). This study evaluated hepcidin secretion and iron burden after LT to elucidate HH pathophysiology. Patients (n=18) homozygous for the p.Cys282Tyr mutation in the HFE gene underwent LT between 1999 and 2008. Serum iron, serum hepcidin, and hepatic iron concentrations were determined before LT and at the end of follow-up (median 57 months). Mortality and causes of death were determined. Survival was compared to that of the overall patient population that received LT. Before LT, serum hepcidin levels were low (0.54 ± 2.5 nmol/L; normal range: 4-30 nmol/L). After LT, 11 patients had iron evaluations; none received iron depletion therapy; all had normal transferrin saturation. The mean serum ferritin was 185 (± 99) μg/L. Magnetic resonance imaging showed that iron overload was absent in nine patients, mild in one patient with metabolic syndrome, and high (180 μmol/g) in one patient with hereditary spherocytosis discovered after LT. At the end of follow-up, serum hepcidin was normal in 10 patients (11.12 ± 7.6 nmol/L; P<0.05) and low in one patient with iron deficiency anemia. Survival was 83% and 67% at 1 and 5 years, respectively. Survival was similar for patients with HH and patients that received LT for other causes.

CONCLUSION

In HH, LT normalized hepcidin secretion and prevented recurrence of hepatic iron overload. Survival was similar to that of patients who received LTs for other liver diseases.

PNPLA3 I148M variant and hepatocellular carcinoma: a common genetic variant for a rare disease

Hepatocellular carcinoma (HCC) is highly associated with chronic liver disease. The rs738409 genetic variant in the patatin-like phospholipase domain-containing 3 (PNPLA3, adiponutrin) gene has been implicated as a genetic determinant of the entire spectrum of liver diseases, ranging from steatosis, chronic hepatitis, cirrhosis and ultimately to HCC. In this review, first we will examine the current genetic theories of disease susceptibility. Next, we will analyze the evidences for the association between PNPLA3 I148M variant and HCC. Moreover, we will exploit this association to propose a new paradigm in human genetics: a common genetic variant contributing to a rare disease. Finally, we will examine the molecular genetics of PNPLA3 and, specifically, the theories that have been proposed to explain the function of PNPLA3 in health and disease.

Molecular diagnosis of hemochromatosis

INTRODUCTION

The discovery of hemochromatosis genes and the availability of molecular-genetic tests considerably modified the knowledge of the disease relative to physiopathology, penetrance, and expression, and had major impact in the diagnostic settings.

AREAS COVERED

Hemochromatosis is a heterogenous disorder at both genetic and phenotypic level. The review discusses criteria to define patients' iron phenotype and to use molecular tests to diagnose HFE-related and non-HFE hemochromatosis. The material examined includes articles published in the journals covered by PubMed US National Library of Medicine. The author has been working in the field of iron overload diseases for several years and has contributed 18 of the papers cited in the references.

EXPERT OPINION

Hemochromatosis genotyping is inseparable from phenotype characterization. A full clinical assessment is needed and DNA test performed when data suggest a clear indication of suspicion of being at risk for HH. HFE testing for p.Cys282Tyr mutation and p.His63Asp variant is the first molecular diagnostic step. Genotyping for rare mutations can be offered to patients with negative first-level HFE testing who have iron overload with no other explanation and should be performed in referral centers for iron overload disorders that can provide genetic advice and in-house genotyping services.

Effect of the A736V TMPRSS6 polymorphism on the penetrance and clinical expression of hereditary hemochromatosis

BACKGROUND & AIMS

Hereditary hemochromatosis (HH) is most frequently related to homozygosity for the p.C282Y HFE mutation (C282Y(+/+)), hampering hepcidin induction in response to iron. The rs855791 polymorphism, encoding for the p.A736V variant of TMPRSS6 regulating hepcidin, influences iron status in the population. The aim of this study was to assess the influence of rs855791 on the penetrance and clinical expression of HH.

METHODS

We retrospectively considered 315 HH patients (163 C282Y(+/+), and 152 with other HFE genotypes) evaluated at the time of diagnosis, and 271 healthy controls with normal iron parameters, residents of Northern Italy; TMPRSS6 genotype was assessed by allele specific polymerase chain reaction.

RESULTS

The p.736V variant determining higher hepcidin release was under-represented in the patients (p=0.0023), independently of the presence of the C282Y(+/+) genotype, and the p.736V/V genotype protected from HH independently of age and sex (OR of HH for p.736A/A: 2.57, 1.3-4.1 and for p.736A/V: 1.84, 1.1-3.2). In the 96 C282Y(+/+) male patients without chronic viral hepatitis and alcohol abuse, the "high hepcidin" p.736V allele was negatively associated with cirrhosis independently of age, ferritin, ALT levels, and alcohol intake (OR 3.93, 95% C.I. 1.17-14.61 for the p.736A variant), and with the cumulative incidence of hepatocellular carcinoma (17% p.736A/A, 4% p.736A/V, 0 p.736V/V, p=0.05).

CONCLUSIONS

The p.A736V TMPRSS6 polymorphism is likely a modifier of HH expression. Additional studies are warranted to validate these findings in other cohorts and test their potential relevance for the clinical management of HH patients.

Clinical cofactors and hepatic fibrosis in hereditary hemochromatosis: the role of diabetes mellitus

The risk of hepatic fibrosis and cirrhosis in hereditary hemochromatosis relates to the degree of iron loading, but iron alone does not explain the variability in disease penetrance. This study sought to identify clinical cofactors that increase the risk of progressive liver disease. We identified 291 patients from our database who were homozygous for the C282Y mutation in HFE and had undergone a liver biopsy with quantification of hepatic iron concentration (HIC) and fibrosis staging. Data were collected from a retrospective chart review, including age, gender, alcohol consumption, medical therapy, smoking history, metabolic risk factors, mobilizable iron, and laboratory results. Male gender, excess alcohol consumption, HIC, and the presence of diabetes were independently associated with increasing fibrosis stage in multivariate analysis. Of these, the presence of diabetes showed the strongest association (odds ratio, 7.32; P = 0.03). The presence of steatosis was associated with higher fibrosis scores, but this was of borderline statistical significance. Risk factors for hepatic steatosis were male gender, impaired glucose tolerance, and increased body mass index.

CONCLUSION

The presence of diabetes was associated with more severe hepatic fibrosis independent of iron loading, male gender, and alcohol consumption. The mechanism for this association is unknown and deserves further evaluation; however, it is possible that diabetes produces an additional hepatic oxidative injury from hyperglycemia. Thus, management of such cofactors in patients with hemochromatosis is important to reduce the risk of liver injury and fibrosis.

Patatin-like phospholipase domain containing-3 gene I148M polymorphism, steatosis, and liver damage in hereditary hemochromatosis

AIM: To investigate whether the patatin-like phospholipase domain containing-3 gene (PNPLA3) I148M polymorphism is associated with steatosis, fibrosis stage, and cirrhosis in hereditary hemochromatosis (HH).

METHODS: We studied 174 consecutive unrelated homozygous for the C282Y HFE mutation of HH (C282Y+/+ HH) patients from Northern Italy, for whom the presence of cirrhosis could be determined based on histological or clinical criteria, without excessive alcohol intake (< 30/20 g/d in males or females) or hepatitis B virus and hepatitis C virus viral hepatitis. Steatosis was evaluated in 123 patients by histology (n = 100) or ultrasound (n = 23). The PNPLA3 rs738409 single nucleotide polymorphism, encoding for the p.148M protein variant, was genotyped by a Taqman assay (assay on demand, Applied Biosystems). The association of the PNPLA3 I148M protein variant (p.I148M) with steatosis, fibrosis stage, and cirrhosis was evaluated by logistic regression analysis.

RESULTS: PNPLA3 genotype was not associated with metabolic parameters, including body mass index (BMI), the presence of diabetes, and lipid levels, but the presence of the p.148M variant at risk was independently associated with steatosis [odds ratio (OR) 1.84 per p.148M allele, 95% confidence interval (CI): 1.05-3.31; P = 0.037], independently of BMI and alanine aminotransaminase (ALT) levels. The p.148M variant was also associated with higher aspartate aminotransferase (P = 0.0014) and ALT levels (P = 0.017) at diagnosis, independently of BMI and the severity of iron overload. In patients with liver biopsy, the 148M variant was independently associated with the severity (stage) of fibrosis (estimated coefficient 0.56 ± 0.27, P = 0.041). In the overall series of patients, the p.148M variant was associated with cirrhosis in lean (P = 0.049), but not in overweight patients (P = not significant). At logistic regression analysis, cirrhosis was associated with BMI ≥ 25 (OR 1.82, 95% CI: 1.02-3.55), ferritin > 1000 ng/mL at diagnosis (OR 19.3, 95% CI: 5.3-125), and with the G allele in patients with BMI < 25 (OR 3.26, 95% CI: 1.3-10.3).

CONCLUSION: The PNPLA3 I148M polymorphism may represent a permissive factor for fibrosis progression in patients with C282Y+/+ HH.

Cryptogenic chronic hepatitis and its changing guise in adults

Cryptogenic chronic hepatitis is a disease that is unexplained by conventional clinical, laboratory and histological findings, and it can progress to cirrhosis, develop hepatocellular carcinoma, and require liver transplantation. The goals of this review are to describe the changing phenotype of cryptogenic chronic hepatitis in adults, develop a diagnostic algorithm appropriate to current practice, and suggest treatment options. The frequency of cryptogenic hepatitis is estimated at 5.4%. Cryptogenic cirrhosis is diagnosed in 5-30% of patients with cirrhosis, and it is present in 3-14% of adults awaiting liver transplantation. Nonalcoholic fatty liver disease has been implicated in 21-63% of patients, and autoimmune hepatitis is a likely diagnosis in 10-54% of individuals. Viral infections, hereditary liver diseases, celiac disease, and unsuspected alcohol or drug-induced liver injury are recognized infrequently in the current cryptogenic population. Manifestations of the metabolic syndrome heighten the suspicion of nonalcoholic fatty liver disease, and the absence of hepatic steatosis does not discount this possibility. The diagnostic scoring system of the International Autoimmune Hepatitis Group can support the diagnosis of autoimmune hepatitis in some patients. Certain genetic mutations may have disease-specificity, and they suggest that some patients may have an independent and uncharacterized disease. Corticosteroid therapy is effective in patients with autoimmune features, and life-style changes and specific therapies for manifestations of the metabolic syndrome are appropriate for all obese patients. The 1- and 5-year survivals after liver transplantation have ranged from 72-85% to 58-73%, respectively.

Accelerated CCl4-induced liver fibrosis in Hjv-/- mice, associated with an oxidative burst and precocious profibrogenic gene expression

Hereditary hemochromatosis is commonly associated with liver fibrosis. Likewise, hepatic iron overload secondary to chronic liver diseases aggravates liver injury. To uncover underlying molecular mechanisms, hemochromatotic hemojuvelin knockout (Hjv-/-) mice and wild type (wt) controls were intoxicated with CCl(4). Hjv-/- mice developed earlier (by 2-4 weeks) and more acute liver damage, reflected in dramatic levels of serum transaminases and ferritin and the development of severe coagulative necrosis and fibrosis. These responses were associated with an oxidative burst and early upregulation of mRNAs encoding α1-(I)-collagen, the profibrogenic cytokines TGF-β1, endothelin-1 and PDGF and, notably, the iron-regulatory hormone hepcidin. Hence, CCl4-induced liver fibrogenesis was exacerbated and progressed precociously in Hjv-/- animals. Even though livers of naïve Hjv-/- mice were devoid of apparent pathology, they exhibited oxidative stress and immunoreactivity towards α-SMA antibodies, a marker of hepatic stellate cells activation. Furthermore, they expressed significantly higher (2-3 fold vs. wt, p<0.05) levels of α1-(I)-collagen, TGF-β1, endothelin-1 and PDGF mRNAs, indicative of early fibrogenesis. Our data suggest that hepatic iron overload in parenchymal cells promotes oxidative stress and triggers premature profibrogenic gene expression, contributing to accelerated onset and precipitous progression of liver fibrogenesis.

Beyond hereditary hemochromatosis: new insights into the relationship between iron overload and chronic liver diseases

Following the model of hereditary hemochromatosis, the possible role of iron overload as a cofactor for disease progression in acquired liver diseases has been investigated with controversial results. In recent years, progress has been made in understanding the regulation of iron metabolism, thereby allowing the evaluation of the mechanisms linking liver diseases to excessive iron accumulation. Indeed, deregulation of the transcription of hepcidin, emerging as the master regulator of systemic iron metabolism, has been implicated in the pathogenesis of hepatic iron overload in chronic liver diseases. Whatever the cause, hepatocellular iron deposition promotes liver fibrogenesis, while an emerging possible aggravating factor is represented by the strong link between iron stores and insulin resistance, a recently recognized risk factor for the progression of liver diseases. Overall, these pathogenic mechanisms, together with the known proliferative and mutagenic effect of excess iron, converge in determining an increased susceptibility to hepatocellular carcinoma. Finally, an association between serum ferritin levels and mortality in patients with end-stage liver disease has recently been reported. Prospective, randomized studies are required to evaluate whether iron depletion may reduce fibrosis progression, hepatocellular carcinoma development, and eventually mortality in patients with chronic liver diseases.