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Understanding iron homeostasis through genetic analysis of hemochromatosis and related disorders.

Genetic analysis of hemochromatosis has led to the discovery of a number of genes whose mutations disrupt iron homeostasis and lead to iron overload. The introduction of molecular tests into clinical practice has provided a tool for early diagnosis of these conditions. It has become clear that hemochromatosis includes a spectrum of disorders that range from simple biochemical abnormalities to chronic asymptomatic tissue damage in midlife to serious life-threatening diseases in young subjects. Molecular studies have identified the systemic loop that controls iron homeostasis and is centered on the hepcidin-ferroportin interaction. The complexity of this regulatory pathway accounts for the genetic heterogeneity of hemochromatosis and related disorders and raises the possibility that genes encoding components of the pathway may be modifiers of the main genotype. Molecular diagnosis has improved the classification of the genetic conditions leading to iron overload and identified novel entities, characterized by both iron loading and variable degrees of anemia. Despite the progress in the diagnosis, classification, and mechanisms of iron overload disorders, the treatment of affected patients continues to rely on regular phlebotomy. Understanding the molecular circuitry of iron control may lead to the identification of potential therapeutic targets for novel treatment strategies to be used in association with or as an alternative to phlebotomy.

Genetic Predisposition to Disease↗

Reversal of cardiac complications by deferiprone and deferoxamine combination therapy in a patient affected by a severe type of juvenile hemochromatosis (JH).

Juvenile hemochromatosis (JH) is a rare autosomal recessive disorder of iron metabolism, genetically heterogeneous. In JH, symptomatic organ involvement occurs as early as the second decade of life. Heart failure and/or arrhythmias are the most frequent causes of death. Phlebotomy is the safest, most effective, and most economic therapeutic approach in hemochromatosis patients but is not indicated during the treatment of severe congestive heart failure with unstable hemodynamic status. The treatment of iron overload in these prohibitive clinical situations has to be carried out using iron chelators. We report a case of heart failure in the setting of unrecognized juvenile hemochromatosis successfully treated by the simultaneous administration of deferoxamine and deferiprone. To our knowledge, this is the first patient affected by JH treated with combined chelation regimen.

Adult↗

New mutations inactivating transferrin receptor 2 in hemochromatosis type 3.

Hereditary hemochromatosis usually results from C282Y homozygosity in the HFE gene on chromosome 6p. Recently, a new type of hemochromatosis (HFE3) has been characterized in 2 unrelated Italian families with a disorder linked to 7q. Patients with HFE3 have transferrin receptor 2 (TFR2) inactivated by a homozygous nonsense mutation (Y250X). Here the identification of 2 new TFR2 mutations is reported. In a large inbred family from Campania, a frameshift mutation (84-88 insC) in exon 2 that causes a premature stop codon (E60X) is identified. In a single patient with nonfamilial hemochromatosis, a T-->A transversion (T515A), which causes a Methionine-->Lysine substitution at position 172 of the protein (M172K), has been characterized. TFR2 gene gives origin to 2 alternatively spliced transcripts-the alpha-transcript, which may encode a transmembrane protein, and the beta-transcript, a shorter, possibly intracellular variant. Based on their positions, the effects of the identified mutations on the 2 TFR2 forms are expected to differ. Y250X inactivates both transcripts, whereas E60X inactivates only the alpha-form. M172K has a complex effect: it causes a missense in the alpha-form, but it may also prevent the beta-form production because it affects its putative initiation codon. Analysis of the clinical phenotype of 13 HFE3 homozygotes characterized at the molecular level has shown a variable severity, from nonexpressing patients to severe clinical complications. The identification of new mutations of TFR2 confirms that this gene is associated with iron overload and offers a tool for molecular diagnosis in patients without HFE mutations.

Adolescent↗

A liver fibrosis cocktail? Psoriasis, methotrexate and genetic hemochromatosis.

BACKGROUND: Pathologists are often faced with the dilemma of whether to recommend continuation of methotrexate therapy for psoriasis within the context of an existing pro-fibrogenic risk factor, in this instance, patients with genetic hemochromatosis. CASE PRESENTATIONS: We describe our experience with two male psoriatic patients (A and B) on long term methotrexate therapy (cumulative dose A = 1.56 gms and B = 7.88 gms) with hetero- (A) and homozygous (B) genetic hemochromatosis. These patients liver function were monitored with routine biochemical profiling; apart from mild perivenular fibrosis in one patient (B), significant liver fibrosis was not identified in either patient with multiple interval percutaneous liver biopsies; in the latter instance this patient (B) had an additional risk factor of partiality to alcohol. CONCLUSION: We conclude that methotrexate therapy is relatively safe in patients with genetic hemochromatosis, with no other risk factor, but caution that the risk of fibrosis be monitored, preferably by non-invasive techniques, or by liver biopsy.

Dermatologic Agents↗

Multiple hormone deficiencies in children with hemochromatosis.

Patients with thalassemia major require multiple blood transfusions leading to hemochromatosis. These patients often have pubertal delay and growth failure, the etiology of which has not been fully elucidated. We performed an extensive endocrine evaluation which included measurements of spontaneous and stimulated levels of gonadotropins, GH, thyroid hormone, and adrenal hormones in 17 patients between the ages of 12 and 18 yr with hemochromatosis receiving desferoxamine therapy. All of the 17 patients had at least one endocrine abnormality, and 12 had more than one abnormality. Abnormalities of the hypothalamic-pituitary-gonadal axis were the most common. Six patients had clinical evidence of delayed puberty with spontaneous and stimulated gonadotropin and sex steroid levels appropriate for their delayed pubertal stage. All 14 children in puberty LH pulsatility index below the mean for pubertal stage compared to normal children. Six of the 14 had LH pulsatility index more than 2 SD below the mean for pubertal stage. This may be an indicator of abnormal pituitary function. Six patients failed either the provocative GH tests (peak GH < 7 micrograms/L) or had a mean spontaneous GH less than 1 microgram/L. The 4 patients who failed provocative tests had growth velocities more than 2 SD below the mean for bone age. Three patients had evidence of primary hypothyroidism. We conclude that all patients with hemochromatosis need periodic careful endocrine evaluations because the incidence of endocrine dysfunction is substantial and they may benefit from hormonal therapy.

Adolescent↗

Non-responsiveness of serum gonadotropins and testosterone to pulsatile GnRH in hemochromatosis suggesting a pituitary defect.

We investigated the potential pituitary origin of gonadal insufficiency in hemochromatosis. Gonadotropin secretion was studied in seven patients with hemochromatosis and hypogonadism, before and after chronic pulsatile GnRH therapy. Pulsatile LH secretion was studied before (sampling every 10 min for 6 h) and after 15-30 days of chronic pulsatile GnRH therapy (10-12 micrograms per pulse). Prior to GnRH therapy, all the patients had low serum testosterone, FSH and LH levels. LH secretion was non-pulsatile in four patients, while a single pulse was detected in the remaining three. Chronic pulsatile GnRH administration did not increase serum testosterone levels; similarly, serum LH levels remained low: neither pulse frequency nor pulse amplitude was modified. We conclude that hypogonadism in hemochromatosis is due to pituitary lesions.

Adolescent↗

[Hereditary hemochromatosis. Case report and review of the literature].

BACKGROUND: HFE-associated hemochromatosis is one of the most common inherited liver disease in Caucasian populations and refers to the association of increased iron stores with tissue damage (e.g., cirrhosis, diabetes, cardiomyopathy), which is progressive when diagnosis and treatment are delayed. AIMS: Description of a case of hereditary hemochromatosis in an asymptomatic 44-years-old patient, whose diagnosis was made through casual identification of abnormal iron markers. We will also present a brief review of the literature about the topic. CONCLUSIONS: Hereditary hemochromatosis is an ideal disease for primary prevention since the disease can be detected well before serious complications develop. This intervention has been shown to prevent the manifestations of the disease, altering its natural history.

Adult↗

Chronic inflammatory demyelinating polyneuropathy associated with idiopathic hemochromatosis.

We describe a 50-year-old woman who developed chronic inflammatory demyelinating polyneuropathy (CIDP) one year after onset of hemochromatosis. Electrodiagnostic studies showed evidence of multifocal demyelination. Marked hypergammaglobulinemia with positive anti-nuclear and anti-DNA antibodies was found. Corticosteroid treatment resulted in a significant lessening of neurological symptoms. This is the first case of CIDP with hemochromatosis. The association may be coincidental, but the altered immune system by hemochromatosis was possibly related to the development of CIDP in this patient.

Adrenal Cortex Hormones↗

An autopsy case of hemochromatosis and hepatoma combined with hereditary spherocytosis.

A case of hemochromatosis and hepatocellular carcinoma secondary to hereditary spherocytosis is very rare and this is only the second case reported in an English language bulletin. When the patient, a 56 years old man, was admitted for receiving cholecystectomy for cholelithiasis, a diagnosis of hemochromatosis secondary to hereditary spherocytosis was made by liver biopsy and hematological examination data. The patient did not receive a blood transfusion nor was administered iron during the entire duration of the illness. Hepatoma was suspected at the time of splenectomy which was performed in 1981 because of severe anemia. Eight months later he died of massive abdominal cavity bleeding and subsequent autopsy findings were consistent with the disease mentioned above. Clinical and postmortem examinations suggested that conspicuously enhanced erythropoiesis in the bone marrow and unknown factors may be responsible for an increase in iron absorption from the gut and in the amount of stored body iron, leading to the development of hemochromatosis.

Aged↗

Was Beethoven's cirrhosis due to hemochromatosis?

Dr. Wagner's description of an advanced macronodular cirrhosis is compatible with end-stage liver disease due to a variety of causes. An alcoholic etiology seems more probable than chronic viral hepatitis since such a diagnosis might also account for the chronic pancreatitis, unless it was related to the cholelithiasis. However, Dr. Wagner's description favors a diagnosis of biliary pigment sludge related to hemolysis. Furthermore, the controversy over the extent of Beethoven's alcohol consumption and the absence of mention of pancreatic calcification weakens the case for an alcoholic etiology. On the other hand, Dr. Wagner's emphasis of bluish-green pigmentation of the liver, blackish pigmentation of the spleen, and an arteropathy of the hepatic vessels suggests the probability of hemochromatosis, which diagnosis is also in keeping with Beethoven's medical history. In this regard the composer's history of recurrent obscure abdominal pain, commencing in his third decade, is especially in keeping with hemochromatosis. As many as a third of patients present with recurrent abdominal pain, and eventually up to 40% of cases develop significant abdominal pain in the course of their disease. While some of these cases of abdominal pain have been attributed to hepatoma, ascites, pancreatitis, perisplenitis, or diabetic neuropathy, the majority remain ill-defined (32). Even so, the diagnosis of hemochromatosis remains unproved in the absence of a histological examination and measurement of hepatic iron concentration. It is proposed that the combined additive, toxic effects of alcohol and iron were the most likely cause of Beethoven's cirrhosis.

Austria↗

Hypogonadism in hemochromatosis: reversal with iron depletion.

Gonadal function was evaluated in 64 persons homozygous for the HLA-linked hemochromatosis allele. Of 41 men, 10 had reduced libido or impotence and 6 had testicular atrophy. Before treatment, 5 men had below normal testosterone concentrations, 4 of whom also had low gonadotrophin levels. Four hypogonadal men were reevaluated after iron depletion treatment. In 2, 1 with primary and another with secondary hypogonadism, testosterone levels returned to normal after phlebotomy and were accompanied by a return of normal sexual function. None of 23 women with hemochromatosis had loss of libido or had a natural menopause before age 45. Our findings indicate that in some men with hereditary hemochromatosis and hypogonadism of either testicular or central origin, sexual function and sex hormone concentrations can be restored to normal after iron depletion therapy.

Adolescent↗

Osteoporosis in hemochromatosis: iron excess, gonadal deficiency, or other factors?

STUDY OBJECTIVE: To define the prevalence, severity, type and pathogenesis of osteopenia in idiopathic hemochromatosis. DESIGN: Prospective study conducted over 18 months. SETTING: Tertiary care center. SUBJECTS: Twenty-two men with idiopathic hemochromatosis and 20 age-matched controls. There were 5 hypogonadal patients, 9 eugonadal nonvenesected patients, and 8 eugonadal venesected patients. MEASUREMENTS AND MAIN RESULTS: All patients and controls were evaluated by spinal radiography, spinal and forearm bone mineral density estimations, dynamic skeletal histomorphometry, and serum biochemistry. Ten patients (45%; 95% CI, 24% to 68%) had osteoporosis as defined by spinal and forearm bone density measurements. Trabecular bone volumes were significantly reduced in the patients (the difference in means between patients and age-matched controls was 3.9%; CI, 1.3% to 6.7%). No patient had osteomalacia. Hypogonadal men had lower bone mass measurements than eugonadal men (radial bone density: beta coefficient = -20.5; CI, -29.2 to -11.8; trabecular bone volume: beta coefficient = -7.1; CI, -10.8 to -3.3). Osteoid and osteoblastic surfaces and bone formation rates were significantly greater in the eugonadal venesected compared with the eugonadal nonvenesected persons (P less than 0.05 for all measurements). CONCLUSIONS: A significant decrease in bone density is seen in idiopathic hemochromatosis, particularly when hypogonadism is present. Low serum free-testosterone concentrations rather than the calciotrophic hormones determine bone mass in this condition.

Adult↗

Screening for hemochromatosis and iron deficiency in employees and primary care patients in Western Germany.

BACKGROUND: Many physicians still believe that iron overload (hemochromatosis) is an uncommon disorder. OBJECTIVE: To estimate the frequency of iron overload and iron deficiency in a group of employees and a group of outpatients. DESIGN: Prospective screening study. SETTING: Western Germany. PARTICIPANTS: 3012 asymptomatic employees and 3027 outpatients of nine practitioners. MEASUREMENTS: Serum ferritin levels and transferrin saturation were measured. Participants with repeatedly abnormal results had thorough clinical evaluations to identify the cause of iron deficiency or overload. RESULTS: Gross iron overload (elevated transferrin saturation and ferritin levels) was proven by liver biopsy and phlebotomy treatment in 28 participants (0.4% of female outpatients, 0.7% of male outpatients, 0.2% of female employees, and 0.4% of male employees) and in six siblings of these participants. Of the 34 participants with iron overload, 30 were precirrhotic. Because 60% of an unselected group of employees with elevated transferrin saturation but normal ferritin levels were assumed to have early hemochromatosis, the prevalence of hemochromatosis was estimated to be 1.8% among patients (1.9% in women and 1.6% in men) and 1.0% among employees (1.1% in women and 1.0% in men). Iron deficiency was found in 6.8% of female patients, 2.4% of male patients, 6.0% of female employees, and 0.5% of male employees. CONCLUSIONS: Iron deficiency was more common in women, and iron overload was more common in men. Among male employees, iron overload was almost as common as iron deficiency.

Adult↗

[Study of the gene of hemochromatosis in first degree relatives of patient with porphyria cutanea tarda].

BACKGROUND: Porphyria cutanea tarda (PCT) is characterized by a deficiency of uroprophyrinogen decarboxylase (URO-D). The activity of this enzyme is decreased in the presence of iron-dependent disorders. A relationship between the hepatic hemosiderosis, which is present in most patients with PCT, and the status of the hemochromatosis gene has been observed. Particularly, two mutations of the gene have been described, one of them (Cys282Tyr) is related to the iron overload and might influence on the development of the clinical signs of PCT. PATIENTS AND METHODS: We have measured the transferrin saturation percentage and observed the status of the hemochromatosis gene in a patient diagnosed with PCT and in five of their relatives. RESULTS: The proband and one sister had a marked increase of uroporphyrins and iron overload, and both had the mutation Cys282Tyr, which was also present in the mother. CONCLUSIONS: This is the first study measuring iron overload and hemochromatosis gene mutations in relatives, and not in patients with PCT. We think that the study of this family justifies the systematic investigation of these parameters in all first degree relatives of patients with PCT, to identify subjects at risk, who can benefit from prophylactic measures and early therapy.

Adult↗

[Diabetes mellitus in hemochromatosis].

The degree of glucose intolerance and diabetes mellitus in hemochromatosis is closely associated with the stage of iron overload and thus also the stage of the accompanying liver disease. Similar to other liver diseases glucose intolerance due to insulin resistance precedes diabetes mellitus also in hemochromatosis. Insulin resistance is probably caused by alterations of insulin or glucose metabolism in the liver and potentially also in extrahepatic peripheral tissue. Diabetes mellitus is found more frequently in iron overload when compared with other forms of chronic liver disease and cirrhosis, respectively. In advanced iron overload, iron accumulation in pancreatic B-cells deteriorates pancreatic insulin secretion and leads to insulin-dependent diabetes mellitus which cannot be reversed by iron removal. In contrast, early alteration of glucose intolerance and insulin resistance may partially be improved by phlebotomies. Thus, in the future we should aim to diagnose hemochromatosis in early stages which are not associated with diabetes mellitus or liver cirrhosis.

Diabetes Mellitus↗

[Molecular genetics of hemochromatosis].

Hemochromatosis is a recessive disorder of iron metabolism characterized by progressive iron loading of parenchymal organs, which accounts for clinical complications such as cirrhosis, diabetes mellitus, cardiopathy, endocrine dysfunctions and arthropathy. Clinical complications, which usually develop after the third or fourth decade of life, can be fatal but may be prevented by phlebotomy if iron excess is detected at a very early stage. The hemochromatosis gene (HFE), located 4.5 megabases telomeric to the HLA-A locus, encodes an HLA class I like protein and two missense mutations, C282Y and H63D in complete disequilibrium have been identified within this gene. Due to its high frequency in the general population, the involvement of H63D in the pathogenesis of the disease remains controversial, and it might correspond to a minor mutation. Conversely, the C282Y mutation is tightly linked to the disease, as it accounts for 80 to 100% of the hemochromatosis cases in Northern Europe. The lower frequency observed, in the patients, in Italy and South of France led to imagine either the implication of other mutations or of other genes. The C282Y mutation is absent in Asia and Africa and is present in the general population with a decreasing gradient of frequency from Northern to Southern Europe. The prevalence of the disease was usually estimated to be 3% but the observed frequency of the C282Y homozygotes is 5% in our breton population raising the question of the penetrance of the disease, and consequently the use of the genotypic test for its systematic screening. As HFE encodes a membrane protein similar to HLA class I protein, its contribution to iron overload is not obvious. The normal protein is predicted to to be expressed at the cell surface in association with beta 2-microglobulin, a localization for which C282Y is critical as it disrupts this association. This protein has also been shown to form a stable complex with the transferrin receptor leading to a decreased affinity for transferrin. A better knowledge of its function will help to decipher iron and different metal-ions metabolism. Although the exact role of the HFE protein is unknown, the genotypic test allows the clinicians to ascertain their diagnosis and genetic counselling.

Genes, MHC Class I↗

Hereditary hemochromatosis among U.S. Army aviators.

From 1988 to 1995, there were five reported cases of hemochromatosis among U.S. Army aviators. Three of the five are presented and discussed. The cases of hereditary hemochromatosis were discovered during unrelated work-ups or from investigation of a positive family history, and not by routine flying duty medical examinations. Recent studies show a prevalence of 5 per 1000 in the general population. This study shows the incidence among Army aviators is 0.296 per 1,000 aviator-years of observation. It is possible that there are cases presently undiagnosed in the Army aviation community. Without screening measures in place, the Army Aviation Branch has greater difficulty diagnosing and treating hereditary hemochromatosis. Heightened awareness and a high clinical index of suspicion are necessary to identify affected patients. Early detection and treatment is essential to prevent long-term end organ damage from iron deposition.

Adult↗

Juvenile hemochromatosis associated with B-thalassemia treated by phlebotomy and recombinant human erythropoietin.

Juvenile hemochromatosis is a rare genetic disorder that causes iron overload. Clinical complications, which include liver cirrhosis, heart failure, hypogonadotropic hypogonadism and diabetes, appear earlier and are more severe than in HFE-related hemochromatosis. This disorder, therefore, requires an aggressive therapeutic approach to achieve iron depletion. We report here the case of a young Italian female with juvenile hemochromatosis who was unable to tolerate frequent phlebotomy because of coexistent ss-thalassemia trait. The patient was successfully iron-depleted by combining phlebotomy with recombinant human erythropoietin.

Adrenal Cortex Hormones↗