Usefulness of erythrocyte ferritin analysis in hereditary hemochromatosis.

A study was carried out to determine the usefulness of erythrocyte ferritin analysis in identifying homozygotes and heterozygotes in families affected with hereditary hemochromatosis, an autosomal recessive disorder. To select the subjects the genotypes of 60 people from 26 affected families were determined by HLA-A and HLA-B haplotyping. In addition, data for 12 homozygotes for whom erythrocyte ferritin values were available from the literature were included. Likelihood analysis was used to evaluate the diagnostic value of erythrocyte ferritin analysis alone and in combination with serum ferritin testing. An erythrocyte ferritin value of 150 ag/cell or higher combined with a serum ferritin level above the 90th percentile indicated homozygosity, whereas a value of less than 150 ag/cell and a serum ferritin level at or below the 90th percentile indicated that homozygosity could be ruled out with a high degree of confidence. The probability of heterozygosity rose to 92% when the erythrocyte ferritin value was between 29 and 149 ag/cell and to 98% when this result was combined with a serum ferritin level at or below the 90th percentile. Erythrocyte ferritin analysis in combination with serum ferritin testing is useful for identifying homozygotes and a proportion of heterozygotes in families affected with hemochromatosis.     

Common variants in the BMP2, BMP4, and HJV genes of the hepcidin regulation pathway modulate HFE hemochromatosis penetrance

Most cases of genetic hemochromatosis (GH) are associated with the HFE C282Y/C282Y (p.Cys282Tyr/p.Cys282Tyr) genotype in white populations. The symptoms expressed by C282Y homozygotes are extremely variable. Only a few suffer from an overt disease. Several studies have suggested that, in addition to environmental factors, a genetic component could explain a substantial part of this phenotypic variation, although very few genetic factors have been identified so far. In the present study, we tested the association between common variants in candidate genes and hemochromatosis penetrance, in a large sample of C282Y homozygotes, using pretherapeutic serum ferritin level as marker of hemochromatosis penetrance. We focused on two biologically relevant gene categories: genes involved in non-HFE GH (TFR2, HAMP, and SLC40A1) and genes involved in the regulation of hepcidin expression, including genes from the bone morphogenetic protein (BMP) regulatory pathway (BMP2, BMP4, HJV, SMAD1, SMAD4, and SMAD5) and the IL6 gene from the inflammation-mediated regulation pathway. A significant association was detected between serum ferritin level and rs235756, a common single-nucleotide polymorphism (SNP) in the BMP2 genic region (P=4.42x10-5). Mean ferritin level, adjusted for age and sex, is 655 ng/ml among TT genotypes, 516 ng/ml in TC genotypes, and 349 ng/ml in CC genotypes. Our results further suggest an interactive effect on serum ferritin level of rs235756 in BMP2 and a SNP in HJV, with a small additive effect of a SNP in BMP4. This first reported association between common variants in the BMP pathway and iron burden suggests that full expression of HFE hemochromatosis is linked to abnormal liver expression of hepcidin, not only through impairment in the HFE function but also through functional modulation in the BMP pathway. Our results also highlight the BMP regulation pathway as a good candidate for identification of new modifier genes.     

A primer for predicting risk of disease in HFE-linked hemochromatosis

Since the discovery of the hemochromatosis gene (HFE) in 1996, there has been increasing interest in diagnostic testing for the C282Y and H63D mutations. The high frequency of these two alleles and their incomplete penetrance in homozygotes and compound heterozygotes make genetic counseling for hemochromatosis different from some other autosomal recessive conditions in that parents and children may also be at risk for iron overload, while homozygotes may remain asymptomatic. We provide a guideline for genetic counseling in HFE-linked hemochromatosis based on the genetic probability of inheriting HFE mutations and known information about expression of iron overload in various HFE genotypes. Genetic probabilities were based on allele frequencies derived from large population studies and Hardy-Weinberg equilibrium estimates. Expression of iron overload in those of various genotypes was based on available estimates of serum ferritin from population screening studies. Estimates for the likelihood of clinical iron overload requiring follow-up screening or treatment are provided by gender and genotype. The probability of inheriting HFE mutations and developing iron overload can be estimated in family members of a proband with HFE mutations. Many C282Y homozygotes will not have clinical iron overload. The risk is highest in men and their C282Y homozygous brothers and significantly lower in homozygous women. Iron overload is uncommon in compound heterozygotes and H63D homozygotes.     

Hereditary hemochromatosis: the clinical significance of the S65C mutation

Hereditary hemochromatosis (HH) is a common genetic disease with iron overload in certain organs, especially the liver. Most cases are homozygous for the C282Y mutation in the HFE gene; a few are C282Y heterozygous, compound C282Y/H63D heterozygous, or have no known mutation. A third mutation, S65C, has been associated with HH, but this finding is disputed. We have studied the clinical significance of various genotypes with the S65C mutation. In a population-based screening for HH in 65,238 persons, 613 had high serum transferrin saturation in two blood samples and were invited for HFE genotyping. In 556 persons with complete data sets, we studied the serum ferritin concentration and the risk of being diagnosed with phenotypic HH in the various genotypic groups. The phenotypic diagnosis was given without knowing the genotypic result. Except for the C282Y homozygotes, no differences in median serum ferritin concentrations were found between the various genotypic groups. However, the C282Y/S65C compound heterozygous group had a higher risk of being diagnosed with phenotypic HH than the wild-type group, as did the C282Y homozygous and the C282Y/H63D compound heterozygous groups. When combined with the C282Y mutation, the S65C mutation is associated with an increased risk of being diagnosed with phenotypic HH.     

Diagnostic efficacy of tests for the detection of iron overload in chronic liver disease.

The value of tests for the detection of body iron overload was investigated in 8 aptients with clinically manifest primary hemochromatosis, 12 patients with cirrhosis and iron overload and 20 patients with liver disease and low or normal iron stores. Iron overload was defined as the presence of stainable iron in more than 50% of hepatocytes in a liver biopsy specimen. The percentages of patients with a true-positive (abnormal) or true-negative (normal) result were: serum iron concentration 65%, transferin saturation 85%, serum ferritin concentration 78%, serum ferritin:serum glutamic oxaloacetic transaminase (SGOT) index 78%, percent iron absorption 58%, percent iron absorption in relation to serum ferritin concetration 80% and percent iron absorption in relation to serum ferritin:SGOT index 93%. The calculated predictive value of a normal test result for the exclusion of iron overload in patients with liver disease, a group with an assumed prevalence of iron overload of 10%, was 98% to 99% for transferrin saturation and serum ferritin concentration used alone and 100% for these measures used together; the predictive value of an abnormal result for the diagnosis of iron overload was less than 50% for all of the above measures used alone or in combination. Hence, in patients with an increased serum ferritin concentration or transferrin saturation, or both, determination of the hepatocellular iron content of a specimen from a percutaneous liver biopsy is required for the diagnosis of iron overload.     

TGF-beta1 codon 25 gene polymorphism is associated with cirrhosis in patients with hereditary hemochromatosis

Hereditary hemochromatosis (HHC) is an autosomal recessive disorder of iron metabolism with variable penetrance. Only a minority of C282Y homozygotes develop clinical overt disease and cirrhosis. The phenotypic heterogeneity of HHC may be due to host genetic factors influencing fibrogenesis such as cytokine gene polymorphisms. In this respect, we investigated the impact of functional genetic polymorphisms of TGF-beta1 (codon 10 Leu/Pro, codon 25 Arg/Pro), TNF-alpha (-308 G/A, -238 G/A) and angiotensinogen (-6 G/A) on the development of cirrhosis in HHC. One hundred and forty-nine (111 male, mean age: 51.0+/-12.9) C282Y homozygotes who underwent liver biopsy were studied. Genotyping was performed by RFLP analysis. TGF-beta1 codon 25 genotypes Arg/Pro and Pro/Pro were more common in patients with cirrhosis than in those without (23.6% vs. 7.4%, p = 0.005). In contrast, the distribution of TGF-beta1 codon 10, TNF-alpha and angiotensinogen genotypes was not different. Logistic regression analysis identified male sex, age, serum ferritin and TGF-beta1 codon 25 Arg/Pro and Pro/Pro as independent predictors for the presence of cirrhosis. The adjusted odds ratio for TGF-beta1 codon 25 Arg/Pro and Pro/Pro was 2.8 (95% CI 1.4-5.7, p = 0.004). In conclusion, C282Y homozygotes carrying TGF-beta1 genotypes Arg/Pro and Pro/Pro are more likely to develop cirrhosis than those with genotype Arg/Arg.     

The enigmatic role of the hemochromatosis protein (HFE) in iron absorption

The HFE gene, a member of the class-I transplantation antigen gene family, is responsible for hereditary hemochromatosis, one of the most common inherited diseases in individuals of European descent. Patients exhibit predictable changes in iron homeostasis, including elevations in both transferrin saturation and serum ferritin levels. A subset of patients progress to overt clinical sequelae, resulting from iron overload. A hallmark of the disease is increased absorption of iron by the intestine. Although the HFE protein appears to modulate the function of the transferrin receptor in vitro, its precise role in vivo remains obscure. With multiple cell types involved in iron metabolism, the function of HFE is likely to be complex.     

Serum indices of body stores of iron in northern fur seals (Callorhinus ursinus) and their relationship to hemochromatosis

Iron storage disease (hemochromatosis) has been reported in many species of both captive and free‐ranging animals. In this study we examined the relationship between this disease and concentrations of iron analytes in aquarium‐held northern fur seals (Callorhinus ursinus). Sera were analyzed for iron, total iron‐binding capacity (TIBC), ferritin, ceruloplasmin, and haptoglobin concentrations in a retrospective study that included samples taken over a 14‐year period. The animals ranged in age from <1 year to an estimated 23 years. Serum ferritin was measured using an enzyme‐linked immunosorbent assay (ELISA) for canine sera. The results from this assay are the first reported for any pinniped. Serum iron concentrations in presumed healthy animals ranged from 37 to 196 µg/dl, and TIBC ranged from 136 to 484 µg/dl. The transferrin saturation percentage differed significantly between male (41%) and female (63%) adult fur seals, as did the ferritin levels (54 ng/ml for males vs. 500 ng/ml for females). There was a trend toward increased serum ferritin and percent transferrin saturation with age, especially in females. The data also showed a relationship between serum iron and transferrin saturation among eight mother–pup pairs, which suggests that pups may develop increased iron levels due to placental transfer of iron and/or transfer of iron through the milk from iron‐overloaded females. Diet was considered as a factor in the development of hemochromatosis in at least three geriatric female northern fur seals, and their diets were analyzed for iron concentrations. On the basis of these results, the diets were altered by replacing a portion of the high‐iron‐content fish (herring) with a lower‐iron‐content item (squid), and discontinuing iron and vitamin C supplementation (via a multivitamin tablet). Sera were analyzed before, and 1 and 4 years after the dietary changes were implemented. Paired t‐tests showed no significant changes in the iron analytes from pre‐ to post‐diet‐change samples, which indicates that it may be too late to affect iron levels by diet alone in older animals with a chronic history of elevated iron levels. Zoo Biol 23:205–218, 2004. © 2004 Wiley‐Liss, Inc.     

Iron chelation with deferasirox in a patient with de-novo ferroportin mutation

Ferroportin disease is a rare type of autosomal dominantly inherited hemochromatosis caused with mutations in the ferroportin gene (SLC40A1). The patients characteristically have hyperferritinemia but normal transferin saturations. Herein, we present a 15-year-old female whose chief complaint was persistent nausea for the last one year. Extensive work-up including brain imaging revealed nothing to explain the etiology of nausea. The serum ferritin level of 1474 ng/mL was suggestive for hemochromatosis syndromes and the molecular testing revealed de-novo c.485_487delTTG (P.Val162del) ferroportin gene mutation. Mild hepatic iron loading, in addition to the cumbersome nausea were accepted as indications for chelation treatment in this particular patient and deferasirox was initiated (10 mg/kg/day) since family did not consent for phlebotomy. Deferasirox was stopped by the 9th month of initiation, since nausea subsided and hepatic iron content was normalized, in order to prevent over chelation. There are no well-established guidelines for the chelation of patients with hereditary hemochromatosis syndromes. However, lifelong monitorization for iron loading and re-initiation of chelation when necessary was planned in our patient.     

Polymorphism in a ferritin H gene from chromosome 6p

Summary This paper addresses the question of whether abnormalities in ferritin expression in the iron storage disease hemochromatosis (HC) involve major deletions or alterations in regions containing the two ferritin H genes that lie near the disease locus on chromosome 6p. We present evidence from analyses of Southern blots that neither gene is deleted in hemochromatosis. We also describe a polymorphism in one of the genes that we have previously shown to be a processed pseudogene. This polymorphism does not correlate with the presence of HC. The PIC value for this polymorphism was calculated as 0.49.     

Increased urinary excretion of 8-iso-prostaglandin F2alpha in patients with HFE-related hemochromatosis: a case-control study

The hypothesis according to which iron overload could be harmful has been extensively and controversially discussed in the literature. One underlying pathological mechanism may be elevated oxidative stress. Thus, we studied the correlation between hemochromatosis and an established marker of oxidative stress, 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha, iPF2alpha-III, 15-F2t-IsoP). We enrolled 21 patients with hemochromatosis, positive for the homozygous C282Y mutation in the HFE gene, and 21 healthy controls frequency-matched by age and gender in a case-control study design. The objective was to show that iron overload in HFE-related hemochromatosis is associated with increased oxidative stress assessed through 8-iso-PGF(2alpha) urinary excretion, and that oxidative stress is impacted by iron-removal treatment (phlebotomy). Study parameters were transferrin saturation, 8-iso-PGF(2alpha) urine excretion, transferrin, ferritin, serum iron, and vitamins A and E for all participants. Iron concentration in the liver and non-transferrin-bound iron were measured in patients only. We found a significant difference in 8-iso-PGF2alpha in patients (245 [interquartile range 157-348] pg/mg creatinine) compared with controls (128 [106-191] pg/mg creatinine, P = 0.002). Vitamin A was significantly reduced in cases (0.34 [0.25-1.83] microg/ml compared to 3.00 [2.11-3.39] microg/ml, P < 0.001), while vitamin E did not show a significant difference in cases (14.7 [11.5-18.1] microg/ml) compared with controls (14.9 [13.1-19.2] microg/ml, P = 0.52). After phlebotomy treatment and normalization of the iron parameters in the hemochromatosis group, serum vitamin A levels were significantly increased (1.36 [1.08-1.97] microg/ml, P = 0.035 vs. baseline, P < 0.001 vs. controls) and 8-iso-PGF2alpha urinary excretion was lowered to control levels (146 [117-198] pg/mg creatinine, P = 0.38 vs. controls). In our study, HFE-related hemochromatosis was associated with increased oxidative stress and hypovitaminemia A in C282Y homozygotes. The increased oxidative stress was reversible by normalization of the iron load by phlebotomy. Thus, phlebotomy is an effective and adequate means for reducing oxidative stress in these patients.     

Enzyme‐linked immunosorbent assay to quantitate serum ferritin in the northern fur seal (Callorhinus ursinus)

Serum ferritin concentration correlates with tissue iron stores in humans, horses, calves, dogs, cats, and pigs. Serum ferritin is considered the best serum analyte to predict total body iron stores in these species, and is more reliable than serum iron or total iron‐binding capacity, both of which may be affected by disorders unrelated to iron adequacy or excess (including hypoproteinemia, chronic infection, hemolytic anemia, hypothyroidism, renal disease, and drug administration). Iron overload has been documented to result in hemochromatosis in captive northern fur seals (Callorhinus ursinus); therefore, we developed an enzyme‐linked immunosorbent assay (ELISA) to measure serum ferritin in this species. The assay uses two murine anti‐canine ferritin monoclonal antibodies in a sandwich arrangement that was originally used in an ELISA to measure serum ferritin in dogs. Ferritin isolated from fur seal liver was used as a standard. Ferritin standards were linear from 0 to 50 ng/ml. Recovery of purified ferritin from fur seal serum varied from 89% to 99%. The within‐assay variability was 6%, and the assay‐to‐assay variability for two different samples was 10% and 16%. Zoo Biol 23:79‐84, 2004.© 2004 Wiley‐Liss, Inc.     

Combined segregation and linkage analysis of genetic hemochromatosis using affection status, serum iron, and HLA.

Characterizing the distribution of parameters of iron metabolism by hemochromatosis genotype remains an important goal vis-à-vis potential screening strategies to identify individuals at genetic risk, since a specific marker to detect the abnormal gene has not been identified as yet. In the present investigation, we analyze serum iron values in ascertained families using a method which incorporates both segregation of the clinical affection status and the HLA linkage information to identify the underlying genotypes. The analysis is performed using an extension of the model presented by Bonney et al., comprising regressive models for segregation analysis and the multipoint linkage strategy implemented in LINKAGE. The gene was found to be completely recessive with respect to both clinical manifestations and serum iron abnormalities, with significant differences in expression by sex. Clinical manifestations were present for all male homozygotes in this data set, suggesting that the recessive hemochromatosis genotype is fully penetrant at all ages in males. This was not the case for younger females. Significant genotype-specific age and sex effects were found for serum iron values. It is interesting that deletion of the HLA marker information did not affect our ability to resolve the genetic model when we analyzed a bivariate phenotype. This serves as a reminder that a search for relevant biological markers can be equally important in discerning the genetic etiology of a disease trait, as a search for linked genetic markers.     

Identification of two human ferritin H genes on the short arm of chromosome 6

We have found by analyses of human-hamster hybrid cells that two human ferritin H genes lie near the locus of the iron storage disease idiopathic hemochromatosis on chromosome 6p. One of these genes was isolated and shown to be a processed pseudogene. Comparison of its sequence with those of other ferritin H pseudogenes indicates that they may be derived from a functional H gene other than that on chromosome 11.     

Plasma ferritin concentrations: their clinical significance and relevance to patient care.

In healthy persons the plasma ferritin concentration is a sensitive index of the size of body iron stores. It has been successfully applied to large-scale surveys of the iron status of populations. It has also proved useful in the assessment of clinical disorders of iron metabolism. A low plasma ferritin level has a high predictive value for the diagnosis of uncomplicated iron deficiency anemia. It is of less value, however, in anemia associated with infection, chronic inflammatory disorders, liver disease and malignant hematologic diseases, for which a low level indicates iron deficiency and a high level excludes it, but intermediate levels are not diagnostic. Measuring the plasma ferritin concentration is also useful for the detection of excess body iron, particularly in idiopathic hemochromatosis, but again it lacks specificity in the presence of active hepatocellular disease. If iron overload is suspected in these circumstances determination of the iron content of a percutaneous liver biopsy specimen is required. In families with idiopathic hemochromatosis the combined determination of the plasma ferritin concentration and the transferrin saturation is a sufficient screen to identify affected relatives; however, estimation of the hepatic iron concentration is required to establish the diagnosis.     

Penetrance of Hemochromatosis in HFE Genotypes Resulting in p.Cys282Tyr and p.[Cys282Tyr];[His63Asp] in the eMERGE Network

Hereditary hemochromatosis (HH) is a common autosomal-recessive disorder associated with pathogenic HFE variants, most commonly those resulting in p.Cys282Tyr and p.His63Asp. Recommendations on returning incidental findings of HFE variants in individuals undergoing genome-scale sequencing should be informed by penetrance estimates of HH in unselected samples. We used the eMERGE Network, a multicenter cohort with genotype data linked to electronic medical records, to estimate the diagnostic rate and clinical penetrance of HH in 98 individuals homozygous for the variant coding for HFE p.Cys282Tyr and 397 compound heterozygotes with variants resulting in p.[His63Asp];[Cys282Tyr]. The diagnostic rate of HH in males was 24.4% for p.Cys282Tyr homozygotes and 3.5% for compound heterozygotes (p < 0.001); in females, it was 14.0% for p.Cys282Tyr homozygotes and 2.3% for compound heterozygotes (p < 0.001). Only males showed differences across genotypes in transferrin saturation levels (100% of homozygotes versus 37.5% of compound heterozygotes with transferrin saturation > 50%; p = 0.003), serum ferritin levels (77.8% versus 33.3% with serum ferritin > 300 ng/ml; p = 0.006), and diabetes (44.7% versus 28.0%; p = 0.03). No differences were found in the prevalence of heart disease, arthritis, or liver disease, except for the rate of liver biopsy (10.9% versus 1.8% [p = 0.013] in males; 9.1% versus 2% [p = 0.035] in females). Given the higher rate of HH diagnosis than in prior studies, the high penetrance of iron overload, and the frequency of at-risk genotypes, in addition to other suggested actionable adult-onset genetic conditions, opportunistic screening should be considered for p.[Cys282Tyr];[Cys282Tyr] individuals with existing genomic data.     

Iron Indices in Bottlenose Dolphins (Tursiops truncatus)

Bottlenose dolphins can have iron overload (that is, hemochromatosis), and managed populations of dolphins may be more susceptible to this disease than are wild dolphins. Serum iron, total iron-binding capacity (TIBC), transferrin saturation, and ferritin were measured in 181 samples from 141 dolphins in 2 managed collections and 2 free-ranging populations. Although no iron indices increased with age among free-ranging dolphins, ferritin increased with age in managed collections. Dolphins from managed collections had higher iron, ferritin, and transferrin saturation values than did free-ranging dolphins. Dolphins with high serum iron (exceeding 300 μg/dL) were more likely to have elevated ferritin but not ceruloplasmin or haptoglobin, demonstrating that high serum levels of iron are due to a true increase in total body iron. A time-series study of 4 dolphins with hemochromatosis that were treated with phlebotomy demonstrated significant decreases in serum ferritin, iron, and TIBC between pre- and posttreatment samples; transferrin saturation initially fell but returned to prephlebotomy levels by 6 mo after treatment. Compared with those in managed collections, wild dolphins were 15 times more likely to have low serum iron (100 μg/dL or less), and this measure was associated with lower haptoglobin. In conclusion, bottlenose dolphins in managed collections are more likely to have greater iron stores than are free-ranging dolphins. Determining why this situation occurs among some dolphin populations and not others may improve the treatment of hemochromatosis in dolphins and provide clues to causes of nonhereditary hemochromatosis in humans.Abbreviations: TIBC, total iron-binding capacityBottlenose dolphins (Tursiops truncatus) are susceptible to iron overload (that is, hemochromatosis).^19,32,33,35 Dolphins with hemochromatosis have high serum iron levels that progress over years, have high transferrin saturation (85% and greater), and are responsive to phlebotomy therapy.¹⁹ Left untreated, dolphins with hemochromatosis are more likely to have increased liver aminotransferases, chronic inflammation, and hyperlipidemia than are healthy controls.³⁵ A 25-y retrospective study of one population demonstrated that 67% of dolphins had excessive hepatic hemosiderin deposition at time of death, 92% of which had hemosiderin deposition in Kupffer cells; hemolytic anemia, anemia of chronic disease, and viral infections were not associated with hemosiderin deposition, and the primary hypothesis is that dolphins in managed collections may be susceptible to iron storage disease.³²The etiology of dolphin iron overload is unknown. The most common cause in humans is hereditary hemochromatosis, which is most often attributed to a point mutation of the HFE gene.¹² Other causes of iron overload include primary liver disease, excessive iron intake, and insulin resistance.^3,36 Comparisons of the HFE gene among dolphins with and without hemochromatosis showed no significant differences (unpublished data), and iron deposition in Kupffer cells (compared with hepatocytes) is not supportive of a hereditary cause.^3,32 Liver enzymes decrease in response to the removal of body iron through phlebotomy; this effect indicates that iron overload leads to liver disease rather than that primary liver disease causes iron overload.¹⁹ At least one dolphin population from which cases of hemochromatosis have been reported have not received iron supplementation for more than 10 y, although the iron content in their frozen–thawed fish diet has not been assessed fully.¹⁹ Dolphins with hemochromatosis have significantly higher 2-h postprandial insulin levels than do controls, suggesting that insulin resistance plays a role in this disease, as occurs in humans.³³In addition to dolphins and humans, iron overload occurs in diverse captive birds, callitrichids, black rhinos, Egyptian fruit bats, lemurs, northern fur seals, California sea lions, tapirs, and Saler cattle.^{5,11,15,18,20,21,23,29,31} Similar to that in other exotic species, iron overload in dolphins is thought to be a disease that is associated with managed care, but comparisons of iron levels among managed collections and free-ranging dolphin populations have been lacking.¹⁹ Further, measurements of serum ferritin, ceruloplasmin, and haptoglobin have not typically been included in iron overload evaluations in dolphins. Although serum ferritin levels can be an indicator of total iron body stores, ferritin also increases in response to inflammation or hemolytic anemia.⁴ In humans, ceruloplasmin is a plasma protein that increases with acute and chronic inflammation and plays a role in iron metabolism. Haptoglobin is a protein that, in humans, decreases with intravascular hemolytic anemia, among other conditions.² As such, concurrent measurements of iron, ferritin, ceruloplasmin, and haptoglobin provide insight into the true cause of changing iron and ferritin levels.Low serum iron is used as a general indicator of inflammation in marine mammals, and return of serum iron to normal levels during illness is seen as a positive indicator for recovery.^13,24 The dynamics of iron, erythrocyte sedimentation rate, and fibrinogen in inflammation have remained important as indicators of dolphin health for decades, yet little has been published about dolphin iron stores and associated acute-phase proteins in the past 30 y.²⁴ One barrier to the use of acute-phase proteins, including C-reactive protein, has been the need for species-specific assays; development of tests that better detect early phases of inflammation and infection could lead to earlier treatment and better outcomes. Other barriers include the need for consecutive samples from dolphins with known health status to validate indicators for inflammation, including ceruloplasmin.To better understand the prevalence of high serum iron and potential risks for hemochromatosis among various dolphin populations, indices of serum iron, ferritin, total iron-binding capacity (TIBC), percentage transferrin saturation, ceruloplasmin, and haptoglobin concentrations were measured in 2 populations of free-ranging dolphins and 2 managed collections, including the cohort of Navy dolphins. These variables were compared by age, sex, and population. Serum ferritin was measured by using a newly developed dolphin-specific assay.     

Diagnostic efficacy of screening tests for hereditary hemochromatosis.

Hereditary hemochromatosis is transmitted as an autosomal recessive trait. Analyses of pedigrees suggest that the frequency of disease (proportion of homozygous individuals) in the general population is approximately 0.3% and that approximately 11% of the population are heterozygous. The genotype of 194 persons in 38 pedigrees was determined by HLA-A and HLA-B haplotyping. Likelihood analysis was then used to appraise the transferrin saturation test when used alone and in combination with the serum ferritin test to detect homozygosity and heterozygosity in these pedigrees. A single cut-off point of 55% for transferrin saturation and a cut-off point at the 90th percentile for the serum ferritin level were adequate for the detection of hemochromatosis if homozygosity was considered to be present when the results of one or both tests were positive. To further assess the value of the transferrin saturation test the percentages were stratified into five intervals. A percentage transferrin saturation of 75 or greater and a serum ferritin level above the 90th percentile ruled in homozygosity, whereas a percentage transferrin saturation of less than 55 and a serum ferritin level at or below the 90th percentile ruled it out with confidence. The probability of heterozygosity rose to 90% when the percentage transferrin saturation was between 35 and 55 and the serum ferritin level was at or below the 90th percentile. The use of five cut-off points allowed the probability of homozygosity and heterozygosity in a pedigree to be estimated for all values of transferrin saturation. Although these screening tests are not recommended for use in the general population, they may be worth while in selected groups of patients.     

Body Iron Stores as Predictors of Insulin Resistance in Apparently Healthy Urban Colombian Men

The aim of this study was to evaluate body iron stores as predictors of insulin resistance. We developed a cross-sectional study among 123 men, 25–64 years of age and determined fasting plasma glucose, insulin, serum ferritin, and C-reactive protein levels. A survey was performed to record personal antecedents and family history of non-transmissible chronic diseases. Log-transformed ferritin levels was an independent predictor for log-transformed insulin resistance index assessed by homeostatic model assessment when body mass index or waist circumference were not included in multiple linear regression models. Sedentarism, heart attack family history, and log-C reactive protein levels were also significant predictors for insulin resistance. In conclusion, documented anthropometric predictors affect the significance of ferritin as a potential prediction variable for insulin resistance. Mechanisms of how body fat could influence ferritin levels should be evaluated. To our knowledge, this is the first evaluation of the relationship between body iron stores and insulin resistance in a Latin American population.     

Pitfalls in the genetic diagnosis of hereditary hemochromatosis

The widespread use of the genotype assay that identifies the common C282Y mutation in the HFE gene has allowed an earlier diagnosis to be made in many subjects. A significant number of these patients may have no evidence of phenotypic disease and have a normal serum ferritin level. This phenomenon is more common when the genotype assay is used to screen populations rather than higher-risk groups such as family members of a proband with hereditary hemochromatosis. Moreover, patients with significant iron overload may be wild type for the C282Y mutation and have no other demonstrable mutation of the HFE gene. The HFE genotype assay has recently been found to give a false-positive C282Y homozygous result in half of the subjects in one population screening study due to the presence of a single nucleotide polymorphism (SNP) that interfered with primer binding in the PCR assay. The problem may be overcome by using alternate primers. A number of other groups have confirmed the finding but in a much smaller number of subjects, whereas others found that their assays were not affected by the SNP. The use of the HFE genotype assay as the sole diagnostic criterion for hereditary hemochromatosis is not recommended. The genotype assay should be used as an adjunct to the established methods of demonstrating iron overload and be viewed as a predictor of either the presence of iron overload or the subsequent development of iron overload during an individual's lifetime.