Anne-Marie Jouanolle

Insulin resistance–associated hepatic iron overload

BACKGROUND & AIMS Hepatic iron overload has been reported in various metabolic conditions, including the insulin-resistance syndrome (IRS) and nonalcoholic steatohepatitis (NASH). The aim of this study was to show that such hepatic iron overload is part of a unique and unrecognized entity. METHODS A total of 161 non-C282Y-homozygous patients with unexplained hepatic iron overload were included. We determined the age; sex; presence of IRS (1 or more of the following: body mass index of >25, diabetes, or hyperlipidemia); serum iron tests and liver iron concentration (LIC; reference value, <36 micromol/g); liver function test results; C282Y and H63D HFE mutations; and liver histological status. RESULTS Patients were predominantly male and middle-aged. Most (94%) had IRS. Transferrin saturation was increased in 35% (median, 42%; range, 13%-94%). LIC ranged from 38 to 332 micromol/g (median, 90 micromol/g), and LIC/age ratio ranged from 0.5 to 4.8 (median, 1.8). Allelic frequencies of both HFE mutations were significantly increased compared with values in normal controls (C282Y, 20% vs. 9%; H63D, 30% vs. 17%), only because of a higher prevalence of compound heterozygotes. Patients with no HFE mutations had similar degrees of iron overload as those with other genotypes, except for compound heterozygotes, who had slightly more iron burden. Steatosis was present in 25% of patients and NASH in 27%. Portal fibrosis (grades 0-3) was present in 62% of patients (grade 2 or 3 in 12%) in association with steatosis, inflammation, and increased age. Sex ratio, IRS, transferrin saturation, and LIC did not vary with liver damage. Serum ferritin concentration, liver function test results, and fibrosis grade were more elevated in patients with steatosis and NASH than in others, but LIC and allelic frequencies of HFE mutations were similar. CONCLUSIONS This study shows that patients with unexplained hepatic iron overload are characterized by a mild to moderate iron burden and the nearly constant association of an IRS irrespective of liver damage.

Phenotypic expression of HFE mutations: A French study of 1110 unrelated iron-overloaded patients and relatives ☆ ☆☆

BACKGROUND & AIMS Two mutations have been described in the HFE gene: C282Y and H63D. The aim of this study was to determine the phenotype of the different HFE genotypes. METHODS Clinical symptoms and iron data were examined according to HFE genotypes in 531 unrelated patients with unexplained liver iron overload and 579 relatives of hemochromatotic patients. RESULTS Non-C282Y +/+ patients did not markedly differ in terms of iron overload or clinical expression according to genotype, except for compound heterozygotes, who had slightly increased transferrin saturation. This contrasted with the strikingly increased expression in C282Y homozygotes. Similar phenotype/genotype correlations were observed in relatives based on serum iron test results. Family transmission of iron overload linked to HFE was exceptional in non-C282Y +/+ siblings and frequent in C282Y homozygotes. CONCLUSIONS Iron overload in patients with the non-C282Y +/+ genotype is mild to moderate, strikingly lower than in C282Y homozygotes, and is not influenced by HFE genotype, except, to a small extent, for compound heterozygotes. The role of H63D mutation therefore seems to be marginal.

A candidate gene for hemochromatosis: frequency of the C282Y and H63D mutations

Abstract The gene whose alteration causes hereditary hemochromatosis (HFE according to the international nomenclature) was, more than 20 years ago, shown to map to 6p21.3. It has since escaped all efforts to identify it by positional cloning strategies. Quite recently, a gene named HLA-H was reported as being responsible for the disease. Two missense mutations, Cys282Tyr (C282Y) and His63Asp (H63D), were observed, but no proof was produced that the gene described is the hemochromatosis gene. To validate this gene as the actual site of the alteration causing hemochromatosis, we decided to look for the two mutations in 132 unrelated patients from Brittany. Our results indicate that more than 92% of these patients are homozygous for the C282Y mutation, and that all 264 chromosomes but 5 carry either mutation. These findings confirm the direct implication of HLA-H in hemochromatosis.

A genotypic study of 217 unrelated probands diagnosed as "genetic hemochromatosis" on "classical" phenotypic criteria.

BACKGROUND/AIMS The HFE gene is a crucial candidate gene for hemochromatosis. The aims of this study were to assess the HFE genotypic profile in a large series of unrelated probands diagnosed as having phenotypic hemochromatosis, to characterize the sub-group of patients who were not homozygous for the major C282Y mutation, and to report the iron status of the detected HFE-identical siblings. METHODS In 217 patients, the phenotypic diagnosis of hemochromatosis was based on strict bioclinical and/or histological criteria, and their genotypic profile (C282Y and H63D mutations) was determined. RESULTS 1) 209 of the 217 probands were C282Y +/+. In 33 cases, an HFE-identical sibling was identified. Two of them had neither a clinical nor a biochemical phenotypic profile of hemochromatosis in the absence of any external factor which might have attenuated this expression. 2) Eight patients (seven males) were not C282Y +/+. Their genotypic profiles were: (C282Y +/-): six cases (four were H63D +/- and two H63D -/-); (C282Y -/-): two cases (one was H63D +/+, one H63D +/-). Phenotypic expression consisted of six cases of mild liver siderosis (among whom were the four compound heterozygotes and one case of alcoholic cirrhosis) and two severe cases of hepatic iron overload (one with alcoholic cirrhosis). Three HFE-identical siblings were identified, none of them presenting with iron excess. CONCLUSIONS In our population: 1) The classical phenotypic criteria fitted, in 96.3% of cases, with a homogeneous genotypic entity defined by homozygosity for the C282Y mutation. Incomplete penetrance of the homozygous status was shown by the absence of the hemochromatosis phenotypic profile in 6% of the HFE-identical siblings. 2) A minority (3.7%) were not homozygous for C282Y. These were essentially men with mild iron overload, and might present with distinct iron overload entity(ies) as suggested by the presence in three of an HFE-identical sibling with absence of iron overload.

Novel mutation in ferroportin 1 gene is associated with autosomal dominant iron overload

We report a family affected with dominant autosomal iron overload related to a new mutation in ferroportin 1, a transmembrane protein involved in the export of iron from duodenal enterocytes and likely from macrophages. The originality of this family is represented by the nature of the mutation consisting in the replacement of glycine 490 with aspartate. Clinicians should be aware of this novel iron overload entity, which corresponds to a particular phenotypic expression (high serum ferritin values contrasting with relatively low transferring saturation, and important Kupffer cell iron deposition as compared to hepatocytic iron excess) with poor tolerance of venesection therapy and a dominant pattern of inheritance. Given this dominant transmission, the mixed Causasian-Asian origin of our Asian proband leaves open the issue of the ethnic origin of the new mutation.

Aceruloplasminemia: new clinical, pathophysiological and therapeutic insights

Aceruloplasminemia is an autosomal recessive disease of iron overload associated with mutation(s) in the ceruloplasmin gene. We report here a new case of aceruloplasminemia in a woman who is a compound heterozygote for two new mutations. Besides this novel genotypic profile, this observation provides new insights on: (i) iron metabolism with normal erythroid repartition, in the absence of serum non-transferrin-bound iron and with an increase of 59Fe plasma clearance; (ii) hepatic abnormalities associated with the presence of iron-free foci; (iii) the therapeutic management of the disease, chronic subcutaneous infusion of deferrioxamine being remarkably effective at reducing hepatic iron overload.

Gender‐specific phenotypic expression and screening strategies in C282Y‐linked haemochromatosis: a study of 9396 French people

Summary. Most features of C282Y‐linked haemochromatosis support the implementation of population screening of the disorder in Caucasians. However, the penetrance of C282Y homozygosity is poorly documented and the strategy for population screening remains debated. Nine thousand three hundred and ninety‐six subjects (3367 men, aged 25–40 years, and 6029 women, aged 35–50 years), attending three Health Appraisal Centres, were genotyped and assessed with respect to clinical and biochemical signs of haemochromatosis. Discriminant, logistic regression and graphic analysis were used to predict homozygosity. Results were validated in 135 homozygotes detected through other family and population studies. Fifty‐four subjects (10 men and 44 women) were homozygous for C282Y. All men had abnormal iron status and most had mild clinical symptoms compatible with haemochromatosis. Identification of all homozygous men required a transferrin saturation (TS) threshold of 50% in the study group (90% specificity) and of 40% in the validation group. Homozygous women differed clinically from non‐homozygotes for the presence of distal arthralgias only (18%vs 6%, P < 0·03). Thirteen (29%) were iron‐deficient (serum ferritin < 13 µg/l) and undetectable by biochemical tests. Although the population studied was not fully representative of the general population, our data strongly suggests that, in young men, large‐scale screening for C282Y homozygosity is justified and can be achieved by using TS prescreening. However, in premenopausal women, large‐scale screening remains to be justified with respect to the natural history of haemochromatosis and should be directly genotypic.

A new missense mutation in the L ferritin coding sequence associated with elevated levels of glycosylated ferritin in serum and absence of iron overload

The best known type of inherited hyperferritinemia not related to iron overload is the hyperferritinemia-cataract syndrome (OMIM #600886), caused by a mutation in the iron-responsive element in the 5-prime non-coding region of the ferritin light chain gene (FTL). This study describes a novel missense mutation of FTL responsible for genetic hyperferritinemia without iron overload. See related perspective article on page 307. Background Elevated serum ferritin levels are frequently encountered in clinical situations and once iron overload or inflammation has been ruled out, many cases remain unexplained. Genetic causes of hyperferritinemia associated to early cataract include mutations in the iron responsive element in the 5’ untranslated region of the L ferritin mRNA, responsible for the hereditary hyperferritinemia cataract syndrome. Design and Methods We studied 91 probands with hyperferritinemia comprising 25 family cases belonging to families with at least two cases of unexplained hyperferritinemia, and 66 isolated cases. In the families, we also analyzed 30 relatives. Hyperferritinemia was considered as unexplained when transferrin saturation was below 45% and/or serum iron below 25 μmol/L and/or no tissue iron excess was detected, when inflammation had been ruled out and when iron responsive element mutation was absent. We carried out sequencing analysis of the FTL gene coding the L ferritin. Results A novel heterozygous p.Thr30Ile mutation in the NH2 terminus of L ferritin subunit was identified in 17 probands out of the cohort. The mutation was shown to cosegregate with hyperferritinemia in all the 10 families studied. No obvious clinical symptom was found associated with the presence of the mutation. This unique mutation is associated with an unusually high percentage of ferritin glycosylation. Conclusions This missense mutation of FTL represents a new cause of genetic hyperferritinemia without iron overload. We hypothesized that the mutation increases the efficacy of L ferritin secretion by increasing the hydrophobicity of the N terminal “A” α helix.

Elevated parathyroid hormone 44-68 and osteoarticular changes in patients with genetic hemochromatosis.

OBJECTIVE To determine whether the osteoarticular changes associated with genetic hemochromatosis could be explained by metabolic parathyroid hormone (PTH) disorders. METHODS The study involved 210 patients with liver iron overload syndromes. Osteoarticular changes were numerically scored as the number of damaged joints. PTH 1-84 and 44-68 were assayed. RESULTS An increase in serum PTH 44-68 levels was found in one-third of untreated patients who had no calcium or PTH 1-84 abnormalities. Serum PTH 44-68 levels correlated positively with serum ferritin levels. In multivariate analyses, the number of affected joints correlated positively with age, serum PTH 44-68 levels, and serum ferritin levels. CONCLUSION Liver iron overload syndromes, especially genetic hemochromatosis, are associated with elevated circulating levels of PTH fragments containing the 44-68 region, which appears to play a role in osteoarticular changes. This increase seems to be a consequence of iron overload.

A novel coding sequence belonging to a new multicopy gene family mapping within the human MHC class I region

The human major histocompatibility complex (MHC) region is a genomic region spanning about 4000 kilobases (kb) including the class I, class II, and class III subregion . The class I subregion is larger than the two others but with fewer genes described to date. It includes a classical human leucocyte antigen (HLA) class I genes (HLA-A, HLA-B, HLA-C) which are highly polymorphic and encode products presenting the endogenous antigenic peptides to the T-cell receptors, and b non-classical class I genes (HLA-E, HLA-F, HLA-G) whose function is still unknown. In this study, we describe the first coding sequence which is not structurally related to the class I genes, although it is localized within the MHC class I region. This novel gene, P5-1, belongs to a multiple copy family, all members of which map within the MHC. Although the P5-1 sequence showed no similarity to sequences in different databanks, its transcription, which is restricted to lymphoid tissues, argues for an immunological function of its product.