Distribution of HFE C282Y and H63D mutations in the Balearic Islands (NE Spain)

Hereditary Hemochromatosis Associated With Idiopathic Refractory Aplastic Anemia in a Five-Year-Old Boy: A Case Report

Hereditary hemochromatosis (HH) is a multisystem disease characterized by iron overload and various clinical presentations, including cirrhosis, diabetes mellitus, and heart failure. HH can be caused by the human homeostatic iron regulator (HFE) and non-HFE gene mutations. Aplastic anemia is a rare, life-threatening bone marrow failure in which fat replaces pluripotent stem cells, resulting in pancytopenia and hypoplasia of bone marrow. We present a case of a five-year-old-boy who initially presented with a large ecchymosis located at the right side of the chest and abdomen. These started suddenly after minor trauma. Later, he was diagnosed with idiopathic aplastic anemia and treated with immunosuppressive therapy (IST). As part of the workup for pancytopenia, we ordered whole exome sequencing (WES) and diagnosed the patient with autosomal recessive hereditary hemochromatosis (ARHH). The ARHH is caused by HFE pathogenic gene mutation variant (c.187C>G p homozygous genotype). After six months of IST, he still had persistent disease. Human leukocyte antigen (HLA) typing showed he has a sister who is a full match but also has ARHH. Because of this, a haploidentical hematopoietic stem cell transplantation (hHSCT) from the father was performed. The hHSCT had a successful outcome. We suggest that in children with idiopathic aplastic anemia, physicians should be aware of the possibility of co-existing hereditary hemochromatosis or secondary hemochromatosis. Serum ferritin and transferrin saturation should also be measured regularly in order to detect early hemochromatosis.

EMQN best practice guidelines for the molecular genetic diagnosis of hereditary hemochromatosis (HH)

Molecular genetic testing for hereditary hemochromatosis (HH) is recognized as a reference test to confirm the diagnosis of suspected HH or to predict its risk. The vast majority (typically >90%) of patients with clinically characterized HH are homozygous for the p.C282Y variant in the HFE gene, referred to as HFE-related HH. Since 1996, HFE genotyping was implemented in diagnostic algorithms for suspected HH, allowing its early diagnosis and prevention. However, the penetrance of disease in p.C282Y homozygotes is incomplete. Hence, homozygosity for p.C282Y is not sufficient to diagnose HH. Neither is p.C282Y homozygosity required for diagnosis as other rare forms of HH exist, generally referred to as non-HFE-related HH. These pose significant challenges when defining criteria for referral, testing protocols, interpretation of test results and reporting practices. We present best practice guidelines for the molecular genetic diagnosis of HH where recommendations are classified, as far as possible, according to the level and strength of evidence. For clarification, the guidelines' recommendations are preceded by a detailed description of the methodology and results obtained with a series of actions taken in order to achieve a wide expert consensus, namely: (i) a survey on the current practices followed by laboratories offering molecular diagnosis of HH; (ii) a systematic literature search focused on some identified controversial topics; (iii) an expert Best Practice Workshop convened to achieve consensus on the practical recommendations included in the guidelines.

Portuguese crypto-Jews: the genetic heritage of a complex history

The first documents mentioning Jewish people in Iberia are from the Visigothic period. It was also in this period that the first documented anti-Judaic persecution took place. Other episodes of persecution would happen again and again during the long troubled history of the Jewish people in Iberia and culminated with the Decrees of Expulsion and the establishment of the Inquisition: some Jews converted to Catholicism while others resisted and were forcedly baptized, becoming the first Iberian Crypto-Jews. In the 18th century the official discrimination and persecution carried out by the Inquisition ended and several Jewish communities emerged in Portugal. From a populational genetics point of view, the worldwide Diaspora of contemporary Jewish communities has been intensely studied. Nevertheless, very little information is available concerning Sephardic and Iberian Crypto-Jewish descendants. Data from the Iberian Peninsula, the original geographic source of Sephardic Jews, is limited to two populations in Portugal, Belmonte, and Bragança district, and the Chueta community from Mallorca. Belmonte was the first Jewish community studied for uniparental markers. The construction of a reference model for the history of the Portuguese Jewish communities, in which the genetic and classical historical data interplay dynamically, is still ongoing. Recently an enlarged sample covering a wide region in the Northeast Portugal was undertaken, allowing the genetic profiling of male and female lineages. A Jewish specific shared female lineage (HV0b) was detected between the community of Belmonte and Bragança. In contrast to what was previously described as a hallmark of the Portuguese Jews, an unexpectedly high polymorphism of lineages was found in Bragança, showing a surprising resistance to the erosion of genetic diversity typical of small-sized isolate populations, as well as signs of admixture with the Portuguese host population.

Hemochromatosis genotypes and risk of iron overload--a meta-analysis

PURPOSE

The incomplete phenotypic penetrance of high iron Fe genotypes in relation to hemochromatosis poses a practical problem in the interpretation of the genotyping results by clinicians. We carried out meta-analyses of the associations between hemochromatosis genotypes C282Y/C282Y, C282Y/H63D, C282Y/wild-type, H63D/H63D, H63D/wild-type, versus wild-type/wild-type and iron overload, both provisional (elevated serum iron markers) and documented (elevated serum iron markers associated with evidence of iron excess based on liver biopsy and/or quantitative phlebotomy).

METHODS

After reviewing 3572 article titles and evaluating 92 articles in detail, odds ratios were pooled from 43 study populations (9986 cases and 25,492 controls) using a random-effects model.

RESULTS

Homozygosity for either variant or compound heterozygosity was associated with both provisional and documented iron overload. Single heterozygosity conferred no risk for elevated hepatic iron index and/or mobilizable iron by quantitative phlebotomy. In patients with clinical hereditary hemochromatosis, no evidence of provisional and documented iron overload with transferrin saturation (TS) values greater than 55% was evidenced for C282Y and H63D single heterozygotes whereas documented iron overload including TS of 45% to 50% was weakly associated with C282Y/wild-type genotype; H63D/H63D genotype was not associated with documented iron overload in patients with TS values of 45% to 50%.

CONCLUSIONS

The results, mainly from case-control studies, cannot necessarily be extrapolated to the general population.

EASL clinical practice guidelines for HFE hemochromatosis

Iron overload in humans is associated with a variety of genetic and acquired conditions. Of these, HFE hemochromatosis (HFE-HC) is by far the most frequent and most well-defined inherited cause when considering epidemiological aspects and risks for iron-related morbidity and mortality. The majority of patients with HFE-HC are homozygotes for the C282Y polymorphism [1]. Without therapeutic intervention, there is a risk that iron overload will occur, with the potential for tissue damage and disease. While a specific genetic test now allows for the diagnosis of HFE-HC, the uncertainty in defining cases and disease burden, as well as the low phenotypic penetrance of C282Y homozygosity poses a number of clinical problems in the management of patients with HC. This Clinical Practice Guideline will therefore, focus on HFE-HC, while rarer forms of genetic iron overload recently attributed to pathogenic mutations of transferrin receptor 2, (TFR2), hepcidin (HAMP), hemojuvelin (HJV), or to a sub-type of ferroportin (FPN) mutations, on which limited and sparse clinical and epidemiologic data are available, will not be discussed. We have developed recommendations for the screening, diagnosis, and management of HFE-HC.

H63D homozygotes with hyperferritinaemia: is this genotype, the primary cause of iron overload?

OBJECTIVES

Hereditary haemochromatosis is a disease that affects iron metabolism and leads to iron overload. Homozygosity for the H63D mutation is associated with increased transferrin saturation (TS) and ferritin levels. Our objective was to find out if the homozygosity of H63D mutation was the primary cause of iron overload.

PATIENTS AND METHODS

We studied 45 H63D homozygotes (31 males and 14 females) with biochemical iron overload and/or clinical features of haemochromatosis. The simultaneous detection of 18 known HFE, TFR2 and FPN1 mutations and sequencing of the HAMP gene were performed to rule out the possible existence of genetic modifier factors related with iron overload.

RESULTS

Values of biochemical iron overload, measured as percentage TS and serum ferritin concentration (SF), in our H63D homozygotes were significantly higher in patients than in controls: TS 55 +/- 15% vs. 35 +/- 15% and SF 764 (645-883) microg/L vs. 115 (108-123) microg/L for patients and controls, respectively. These H63D homozygotes presented extreme hyperferritinaemia and no additional mutations in HFE, TFR2, FPN1 and HAMP genes were detected.

CONCLUSIONS

The lack of additional mutations in our H63D homozygotes suggests that this genotype could be the primary cause of iron overload in these patients. Despite our results, we cannot entirely discount the possibility that one or more genetic modifier factor exists, simply because we were unable to find it, although there was a precedent in the HFE gene. Genetic modifier factors have been described for C282Y mutations in the HFE gene, but at the present time they have never been reported in H63D homozygotes.

Frequency of the hemochromatosis gene (HFE) 282C→Y, 63H→D, and 65S→C mutations in a general Mediterranean population from Tarragona, Spain

Three mutations have recently been detected in the hereditary hemochromatosis HFE gene (282C-->Y, 63H-->D, and 65S-->C). To determine their prevalence in a northeastern Spanish Mediterranean population, we studied 812 subjects between 18 and 75 years of age, randomly selected from the electoral roll of three villages. There were no homozygotes for the 282C-->Y or S65D mutations in this sample. For the 63H-->D mutation, 4.8% were homozygotes; 4.3, 32.3, and 2% were heterozygotes for the 282C-->Y, 63H-->D, and 65S-->C mutations, respectively. The prevalence of compound heterozygotes was 2% for 282C-->Y/63H-->D and 0.6% for 63H-->D /65S-->C. We found no significant differences between men and women. In conclusion, 46% of this Mediterranean population of Spain are carriers of at least one of the three mutations that can increase iron absorption.

Frequency of the C282Y and H63D mutations of the hemochromatosis gene (HFE) in a cohort of 1,000 neonates in Madrid (Spain)

For centuries in Europe, population movements have contributed to ethnic groups, cultures, and consequently, inheritance mixing. There are certain genetic diseases such as hereditary hemochromatosis whose distribution is directly related to the population movements. The objective of the present investigation was to determine the C282Y and H63D mutation frequency of the HFE gene in a cohort study of 1,000 neonates in the Community of Madrid (Spain), thus contributing to the HFE gene mutations distribution research in Europe and establishing the origin of the mutations in Spain. The allelic frequency of C282Y mutation was 1.7% (CI 95% 1.1-2.3) and the H63D allele was present in 16.4% of chromosomes (CI 95% 14.8-18). In Spain, the presence of C282Y mutation and its distribution could be due more to Celtic than to Viking legacy, whereas it is assumed that the one in relation to the H63D variant occurred in the Basque Country during the Paleolithic Period.

Prevalence of HFE C282Y and H63D in Jewish populations and clinical implications of H63D homozygosity

The frequencies of C282Y and H63D mutations of the HFE gene vary between different populations. A previous study showed an unexpectedly high H63D frequency in Chuetas (a population of Jewish descent). The present study addressed the question of the distribution of these mutations in Jewish populations from different origins and studied the possible causes of the high H63D frequency in Chuetas. Moreover, to improve the understanding of the controversial relationship between H63D homozygosity and iron overload, a group of patients with altered iron metabolism were studied. The high frequency of H63D mutation in Chuetas is not due to a high prevalence of this mutation in Sephardic Jews. Jewish populations have low C282Y and moderate H63D frequencies, suggesting slight gene flow from their surrounding populations. In accordance with historical and demographic data, genetic drift is the most probable cause for the singular H63D frequency in Chuetas. Clinically, this study of H63D homozygotes supports the conclusion that this genotype must be taken into account, because it confers an increased risk of iron overload and therefore genetic susceptibility to developing hereditary hemochromatosis or to aggravating other diseases.

Hemocromatosis hereditaria: estudio fenotípico de una población española

BACKGROUND AND OBJECTIVE

Hereditary hemochromatosis (HH) displays an important phenotypic variability and is a disease influenced by many factors.

PATIENTS AND METHOD

We included 88 patients with HH. Main clinical and laboratory data were analyzed, and the influence of 6 variables on intensity of iron overload was evaluated.

RESULTS

In 38.6% (95% confidence interval [CI], 28.5-49.6%) patients, none of the typical symptoms of the disease was observed. 30,9% (95% CI, 21.7-41.7%) showed abnormalities of the glucose metabolism. We detected an increase in sideremia in 75.0% patients (CI 95%, 64.4-83.3%), transferrin saturation index (TSI) in 95.4% (CI 95%, 88.1-98.5%) and ferritin in 93.2% (CI 95%, 85.1-97.1%) of patients. In addition, we observed increased values of GPT and alkaline phosphatase in an appreciable percentage of patients. Ferritin was significantly higher in men (1329.4 [913.2] ng/ml vs 656.6 [644.5] ng/ml; p < 0.001), and in those older than 45 years (1293.9 [1006.9] ng/ml vs 868.9 [642.8] ng/ml; p = 0.023] and in not blood donors (1205.2 [926.8] vs 524.8 [365.9] ng/ml; p < 0.001). TSI was 81.9% (19.6) in C282Y homozygotes and 65.7% (19.2) in the rest of HFE genotypes (p = 0.002). Differences of TSI with regard to sex, age or status of blood donor were not detected. Sideremia was significantly higher in patients infected by virus C (251.8 [24.4] microg/dl vs 182.8 [45.8] microg/dl; p = 0.001).

CONCLUSIONS

HH patients have a noticeable phenotypic variability, and for that reason clinical symptoms are only orientative for the diagnosis. The relationship between HH and glucose metabolism should be investigated further. Iron parameters can be influenced by age, sex, HFE genotype, blood donation, alcohol intake and hepatitis C virus infection.

Frequency ofHFEH63D, S65C, and C282Y Mutations in Patients with Iron Overload and Controls from Toledo, Spain

Hereditary hemochromatosis (HH) is an autosomal recessive disease caused by a defective iron absorption. C282Y is the most frequent HFE gene mutation causing HH in Northern European populations and their descendants. However, two other mutations, H63D and S65C, have been described as pathogenic changes. In this study, we have tried to evaluate the frequency of these three mutations in our community. Eighty-three patients with clinical and/or biochemical features of hemochromatosis and 150 controls were screened for H63D, S65C, and C282Y mutations using a PCR-restriction fragment length polymorphism (RFLP)-based strategy. In contrast to previous studies, 7% of the patients were homozygous for C282Y mutation. The remaining patients were 20% H63D homozygous, 10% H63D/C282Y compound heterozygous, 1% H63D/S65C compound heterozygous, 22% H63D heterozygous, 2% C282Y heterozygous, 2% S65C heterozygous, and 36% of patients lacked any of the three mutations studied, despite the fact that they showed clinical/biochemical features of hemochromatosis. We observed a high frequency of the H63D mutation in both the control group and patients, whereas the main genotypes implicated in HH in our series were H63D homozygous and H63D/C282Y compound heterozygous. We propose that the H63D mutation be analyzed in HH patients from our geographic area. Moreover, further studies are needed to elucidate the role of this mutation in the development of HH and the genetic, environmental or other factors that affect the genotype-phenotype correlation between H63D and hemochromatosis.

Genotipo y expresión fenotípica de la hemocromatosis hereditaria en España

INTRODUCTION

The prevalence of C282Y homozygosity in patients with hereditary hemochromatosis (HH) has been reported to be markedly lower in the Mediterranean Basin than in northern Europe. In Spain, the available data are contradictory and limited to small series in specific regions. The objective of this study is to determine the prevalence of the 2 main HFE gene mutations in a large series of unrelated Spanish patients with HH from different geographical origins.

PATIENTS AND METHOD

The criteria for HH diagnosis were: repeat serum transferrin saturation index (> 45% plus C282Y homozygosity and/or hepatic iron index (> 1.9 of dry liver weight in non-cirrhotic patients or (> 4.1 in patients with liver cirrhosis. Cases in related individuals were excluded. Demographic data, clinical expression, iron parameters and HFE gene mutations (C282Y and H63D) were assessed in 222 patients.

RESULTS

A total of 83.3% of patients were C282Y homozygous and 5% were compound heterozygous (C282Y/H63D). No significant differences in phenotypic expression or in the frequency of C282Y homozygosity were observed between patients born in the North and South of Spain.

CONCLUSION

The genotypic and phenotypic expression of HH in Spain is very similar to that reported in Northern Europe. Thus, the genetic heterogeneity described in some Southern European regions cannot be considered a common feature to all countries of the Mediterranean Basin.

Population screening for hemochromatosis: a study in 5370 Spanish blood donors

BACKGROUND/AIMS

Hereditary hemochromatosis is associated with homozygosity for C282Y mutation in the HFE gene, elevated serum transferrin saturation and excess iron deposits throughout the body. We conducted a population-based study in Spain to asses the prevalence of the HFE mutations and their effect on iron parameters.

METHODS

We screened 5370 blood donors for the C282Y and H63D HFE mutations by allele-specific polymerase chain reaction. Serum iron, serum ferritin and transferrin saturation were also measured.

RESULTS

We have found eight (five men and three women) blood donors who are C282Y homozygotes (0.15%) and 74 C282Y/H63D compound heterozygotes (1.38%). Four out of the eight C282Y homozygotes, all men, had high serum ferritin and transferrin saturation values. No woman was detected with both iron parameters increased. Only one of the 74 C282Y/H63D compound heterozygotes showed elevated serum ferritin and transferrin saturation values (penetrance 1.35%). Serum ferritin and transferrin saturation were significantly higher in C282Y homozygous men as compared with the rest of the genotypes.

CONCLUSIONS

The C282Y/C282Y genotype frequency in Spain is 1 in 1004. The C282Y/C282Y genotype is clearly associated with an increase in iron parameters. Biochemical expression of the disease was found in 80% of the C282Y/C282Y men.