C282Y Homozygous Hemochromatosis Research Articles

THU-389 - The ancestral haplotype HLA-A3 does not influence the likelihood of advanced hepatic fibrosis or cirrhosis in C282Y homozygous hemochromatosis

THU-389 - The ancestral haplotype HLA-A3 does not influence the likelihood of advanced hepatic fibrosis or cirrhosis in C282Y homozygous hemochromatosis

The ancestral haplotype markers HLA -A3 and B7 do not influence the likelihood of advanced hepatic fibrosis or cirrhosis in HFE hemochromatosis

Advanced hepatic fibrosis occurs in up to 25% of individuals with C282Y homozygous hemochromatosis. Our aim was to determine whether human leukocyte antigen (HLA)-A3 and B7 alleles act as genetic modifiers of the likelihood of advanced hepatic fibrosis. Between 1972 and 2013, 133 HFE C282Y homozygous individuals underwent clinical and biochemical evaluation, HLA typing, liver biopsy for fibrosis staging and phlebotomy treatment. Hepatic fibrosis was graded according to Scheuer as F0–2 (low grade hepatic fibrosis), F3–4 (advanced hepatic fibrosis), and F4 cirrhosis. We analysed associations between the severity of fibrosis and HLA-A3 homozygosity, heterozygosity or absence, with or without the presence of HLA-B7 using categorical analysis. The mean age of HLA-A3 homozygotes (n = 24), heterozygotes (n = 65) and HLA-A3 null individuals (n = 44) was 40 years. There were no significant differences between the groups for mean(± SEM) serum ferritin levels (1320 ± 296, 1217 ± 124, 1348 ± 188 upmug/L), hepatic iron concentration (178 ± 26, 213 ± 22, 199 ± 29 upmumol/g), mobilizable iron stores (9.9 ± 1.5, 9.5 ± 1.5, 11.5 ± 1.7 g iron removed via phlebotomy), frequency of advanced hepatic fibrosis (5/24[12%], 13/63[19%], 10/42[19%]) or cirrhosis (3/24[21%], 12/63[21%], 4/42[24%]), respectively. The presence or absence of HLA-B7 did not influence the outcome. Thus, HLA-A3 and HLA-B7 alleles are not associated with the risk of advanced hepatic fibrosis or cirrhosis in C282Y hemochromatosis.

Effects of Highly Conserved Major Histocompatibility Complex (MHC) Extended Haplotypes on Iron and Low CD8+ T Lymphocyte Phenotypes in HFE C282Y Homozygous Hemochromatosis Patients from Three Geographically Distant Areas

Hereditary Hemochromatosis (HH) is a recessively inherited disorder of iron overload occurring commonly in subjects homozygous for the C282Y mutation in HFE gene localized on chromosome 6p21.3 in linkage disequilibrium with the human leukocyte antigen (HLA)-A locus. Although its genetic homogeneity, the phenotypic expression is variable suggesting the presence of modifying factors. One such genetic factor, a SNP microhaplotype named A-A-T, was recently found to be associated with a more severe phenotype and also with low CD8+T-lymphocyte numbers. The present study aimed to test whether the predictive value of the A-A-T microhaplotype remained in other population settings. In this study of 304 HH patients from 3 geographically distant populations (Porto, Portugal 65; Alabama, USA 57; Nord-Trøndelag, Norway 182), the extended haplotypes involving A-A-T were studied in 608 chromosomes and the CD8+ T-lymphocyte numbers were determined in all subjects. Patients from Porto had a more severe phenotype than those from other settings. Patients with A-A-T seemed on average to have greater iron stores (p = 0.021), but significant differences were not confirmed in the 3 separate populations. Low CD8+ T-lymphocytes were associated with HLA-A*03-A-A-T in Porto and Alabama patients but not in the greater series from Nord-Trøndelag. Although A-A-T may signal a more severe iron phenotype, this study was unable to prove such an association in all population settings, precluding its use as a universal predictive marker of iron overload in HH. Interestingly, the association between A-A-T and CD8+ T-lymphocytes, which was confirmed in Porto and Alabama patients, was not observed in Nord-Trøndelag patients, showing that common HLA haplotypes like A*01–B*08 or A*03–B*07 segregating with HFE/C282Y in the three populations may carry different messages. These findings further strengthen the relevance of HH as a good disease model to search for novel candidate loci associated with the genetic transmission of CD8+ T-lymphocyte numbers.

Hémochromatose héréditaire : circonstances de découverte et délais diagnostiques

PurposeHereditary hemochromatosis is characterized by an excessive absorption and progressive accumulation of iron in the liver, the pancreas, the heart, and the joints. Tiredness and joint manifestations occur usually before hepatopathy, diabetes or cardiopathy. Such common and unspecific symptoms seem to be largely unknown and important diagnostic delays have been reported. The aim of this study was to investigate the discovery circumstances and the diagnostic delay. MethodsA survey was carried out amongst French patients with C282Y homozygous hemochromatosis who were contacted through patients associations or blood centers. ResultsThe questionnaire was answered by 374 patients. Mean age at diagnosis was 48.6±11.9years. In 53% of the cases, the serum level of ferritin was greater than 1000 μg/L. Diagnosis was based on family genetic survey (29%), or fortuitous analyses showing an abnormal serum ferritin (26%), or clinical manifestations (45%). Main complaints were joint pain, tiredness or liver disease. Only 2.1% consulted for diabetes, cardiopathy or changed complexion. Time to diagnosis was lower than 1 year for 98% of patients who presented with fatigue but from 1 to 15 years for 23.4% and 29% of patients who presented with arthropathy and hepatopathy, respectively. ConclusionFor 55% of patients, diagnosis was based on familial genetic survey or fortuitous abnormal results of blood samples. An initial serum level of ferritin greater than 1000 μg/L was a factor of severity for 50% of patient. These two elements must be taken into account to consider a population mass screening. Long time to diagnosis required a sensitization of the population to be aware of the clinical manifestations of hemochromatosis.

The relationship between iron overload and clinical characteristics in a Spanish cohort of 100 C282Y homozygous hemochromatosis patients

We studied the relationship between iron removed by venesection, sex, age, and clinical characteristics in a group of 100 Spanish probands with hereditary hemochromatosis (HH), all C282Y homozygous in the HFE gene. Iron overload was higher in men than in women (P < 0.0001) and increased with age (P = 0.02). Forty-four patients presented with liver disease (28 had fibrosis-cirrhosis of the liver), 24 with diabetes, 18 with arthropathy, and 13/73 men with impotence. No clinical consequences of hemochromatosis were observed in 43 patients. The number of clinical complications was higher in men (P = 0.01) and increased with age (P = 0.006) and with the amount of iron removed (P < 0.0001). The amount of iron removed was significantly higher by univariate analysis in patients with liver disease (P < 0.0001), diabetes (P = 0.007), arthropathy (P = 0.006), and impotence (P = 0.003) than in patients without these complications. In the multivariant analysis, only liver disease maintained a significant relationship with the amount of iron removed (P < 0.0001). Diabetes and arthropathy were closely related with previous liver disease, and impotence appeared mainly in hemochromatosic men with diabetes and alcoholism.

A study of 82 extended HLA haplotypes in HFE-C282Y homozygous hemochromatosis subjects: relationship to the genetic control of CD8+ T-lymphocyte numbers and severity of iron overload

BackgroundIt has been recently demonstrated that CD8+ T-lymphocyte numbers are genetically transmitted in association with the MHC class I region. The present study was designed with the objective of narrowing the region associated with the setting of CD8+ T-lymphocyte numbers in a population of C282Y homozygous hemochromatosis subjects, in whom a high prevalence of abnormally low CD8+ T-lymphocyte counts has been described.MethodsThe study includes 43 C282Y homozygous subjects fully characterized both phenotypically and genotypically. Clinical characterization includes measurements of iron parameters at diagnosis (transferrin saturation and serum ferritin), total body iron stores and T-cell immunophenotyping determined by flow cytometry. Genetic characterization includes HLA class I alleles (A, B and C) and four additional microsatellite markers (D6S265, D6S2222, D6S105 and D6S2239) spanning 5 Megabases in the 6p21.3 region.ResultsEighty-two extended C282Y carrying haplotypes were defined. Single-locus analysis revealed that the HLA-A region was associated with CD8+ T-cell numbers. Multivariate analysis showed that the combinations of the most common HLA-A alleles (HLA-A*03, -A*02 and -A*01) were associated with significantly lower numbers of CD8+ T-lymphocytes (0.30 ± 0.14 × 106/ml), in comparison with subjects carrying only one copy of those alleles (0.46 ± 0.19 × 106/ml) and subjects without any copy of those alleles (0.79 ± 0.15 × 106/ml;p = 0.0001). No differences were observed in CD8+ T-cell counts among control subjects carrying the same combinations of HLA-A alleles (0.47 ± 0.14; 0.45 ± 0.21 and 0.41 ± 0.17 × 106/ml, respectively), therefore not supporting a direct effect of HLA specificity but rather an indirect association with a locus close to HLA-A. Multivariate analysis showed that the combination of the most common HLA-A alleles also have an impact on the clinical expression of HH in terms of iron stores, in males(p = 0.0009).ConclusionThe present study provides evidence supporting an inextricable link between extended HLA haplotypes, CD8+ T-lymphocyte numbers and severity of iron overload in hereditary hemochromatosis(HH). It gives additional information to better define a candidate region involved in the regulation of CD8+ T-lymphocyte numbers. A new evolutionary hypothesis concerning the inheritance of the phenotype of low CD8+ T-lymphocyte numbers associated with particular ancestral HLA haplotypes carrying the C282Y mutation and its implication on the clinical heterogeneity of HH is discussed.

The C282Y mutation may have been positively selected as it mitigates the infertility of celiac disease

Celiac disease and C282Y homozygous hemochromatosis have a similar increasing incidence across Europe. Both have gradients of frequency which increase from Turkey to North West Europe and culminate with a high frequency in Ireland. These two gradients follow the path of the Neolithic settlers who reached the edge of Europe at Ireland. Celiac disease and C282Y hereditary hemochromatosis have opposite effects on iron absorption and probably on the absorption of some other divalent metals including copper. The C282Y mutation is estimated to be some 2000 years old. Celiac disease is likely a much older disorder. The C282Y mutation may have been positively selected for as it increases absorption of divalent metal ions in celiac disease and thus has a mitigating effect on the infertility which may be associated with celiac disease.

Urine pregnancy test and intrauterine inseminations

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Noninvasive prediction of cirrhosis in C282Y-linked hemochromatosis

The aim of the present study was to examine the predictive accuracy of noninvasive clinical and biochemical variables associated with cirrhosis among patients with C282Y homozygous hemochromatosis. Sixteen clinical and laboratory variables were recorded at the time of diagnosis in 193 Canadian C282Y homozygous patients. All patients underwent percutaneous liver biopsy and 27 (14%) had biopsy specimen–proven cirrhosis. Prediction of cirrhosis was assessed first by univariate regression analysis. Variables significantly related to cirrhosis were then evaluated by stepwise linear multivariate regression. Receiver operating characteristic curve analysis of the most informative variables from multivariate analysis was then used to devise a clinically applicable index for the noninvasive prediction of cirrhosis. This index was then validated in 162 C282Y homozygous patients in France. Ferritin, blood platelets, and aspartate transaminase (AST) level were selected for the clinical index. The combination of ferritin levels of 1,000 μg/L or greater, platelet levels of 200 × 10 9/L or less, and AST levels above the upper limit of normal led to a correct diagnosis of cirrhosis in 77% of Canadian patients. In the French patients, this led to a correct diagnosis of cirrhosis in 90%. In conclusion, in C282Y homozygous patients, a combination of easily measured laboratory variables (ferritin, platelets, AST) can be used to make the diagnosis of cirrhosis in approximately 81% of cases, reducing the need for liver biopsy. (H EPATOLOGY 2002;36:673-678.)

Peripheral lymphocytes and intracellular cytokines in C282Y homozygous hemochromatosis patients

Background/Aims: Several abnormalities in the immune status of hereditary hemochromatosis patients have been reported. We evaluated the peripheral blood lymphocytes phenotype and cytokine profile of CD8 + and CD4 + T cells in C282Y homozygous hereditary hemochromatosis patients compared to control subjects. Methods: Peripheral blood lymphocytes from 17 asymptomatic patients and 14 control subjects were analyzed. We determined the distribution of lymphocyte subsets and investigated at single-cell level by flow-cytometry the potential of cytokines production. The frequency of cytokine (interferon gamma, tumor necrosis factor alpha, interleukin 2 (IL-2), IL-4, IL-5, IL-10 and IL-13) producing cells was assessed in total T-lymphocytes, CD3 +CD8 + and CD3 +CD4 + subsets. Results: The patients studied showed a significant decrease of total lymphocyte count, T CD4 +CD3 +, CD28 +, CD8 +CD28 + lymphocytes and natural killer (NK) CD56 +CD16 +CD3 − cells. The reduction of CD28 + and CD8 +CD28 + lymphocyte count was inversely related to transferrin saturation index. An increase in the ability of T-cells to produce all the cytokines studied and a major increase in IL-4 and IL-10 production in the CD3 +CD8 + subset was found. Our results demonstrate that activated Th1 and Th2 lymphocytes coexist in the peripheral blood of hereditary hemochromatosis patients and that T-cytotoxic (Tc) 2 subset is more expanded than in control population. Conclusions: The association of a decreased number of T CD8 + cytotoxic lymphocytes and NK cells, and the development of Tc2 cells in asymptomatic C282Y homozygous patients represents an imbalance in their immune function that might contribute to the high incidence of hepatocarcinoma.

Excess alcohol greatly increases the prevalence of cirrhosis in hereditary hemochromatosis

Background & Aims:The progression of fibrosis to cirrhosis is the most significant prognostic factor in hereditary hemochromatosis. We aimed to determine the range of hepatic iron concentration associated with cirrhosis in the absence of alcohol and other pro-fibrogenic cofactors and to quantify the contribution of excess alcohol consumption to the development of cirrhosis.Methods:Liver biopsy data were evaluated on 224 C282Y homozygous hemochromatosis subjects. To determine the effect of alcohol alone on the development of fibrosis, subjects with viral hepatitis or nonalcoholic steatohepatitis were excluded. Subjects were divided into those who consumed less than 60 g alcohol per day and those who consumed 60 g per day or more.Results:Seven percent of subjects who consumed less than 60 g per day had severe fibrosis/cirrhosis compared with 61% of excess alcohol consumers.Conclusions:Hemochromatosis subjects who drink more than 60 g alcohol per day are approximately 9 times more likely to develop cirrhosis than those who drink less than this amount, and the range of hepatic iron concentration associated with cirrhosis in the absence of cofactors was 233–675 μmol/g dry weight.