Juvenile hemochromatosis in the southeastern United States: a report of seven cases in two kinships

Novel compound heterozygous mutations in the hemojuvelin gene in a juvenile hemochromatosis patient: A case report

BACKGROUND

Juvenile hemochromatosis (JH) is an early-onset, rare autosomal recessive disorder of iron overload observed worldwide that leads to damage in multiple organs. Pathogenic mutations in the hemojuvelin (HJV) gene are the major cause of JH.

CASE SUMMARY

A 34-year-old male Chinese patient presented with liver fibrosis, diabetes, hypogonadotropic hypogonadism, hypophysis hypothyroidism, and skin hyperpigmentation. Biochemical test revealed a markedly elevated serum ferritin level of 4329 μg/L and a transferrin saturation rate of 95.4%. Targeted exome sequencing and Sanger sequencing revealed that the proband had a novel mutation c.863G>A (p.R288Q) in the HJV gene which was transmitted from his father, and two known mutations, c.18G>C (p.Q6H) and c.962_963delGCinsAA (p.C321*) in cis, which were inherited from his mother. The p.R288W mutation was previously reported to be pathogenic for hemochromatosis, which strongly supported the pathogenicity of p.R288Q reported for the first time in this case. After 72 wk of intensive phlebotomy therapy, the patient achieved a reduction in serum ferritin to 160.5 μg/L. The patient's clinical symptoms demonstrated a notable improvement.

CONCLUSION

This study highlights the importance of screening for hemochromatosis in patients with diabetes and hypogonadotropic hypogonadism. It also suggests that long-term active phlebotomy could efficiently improve the prognosis in severe JH.

Endocrine dysfunction in hereditary hemochromatosis

Hereditary hemochromatosis (HH) is a genetic disorder of iron overload and subsequent organ damage. Five types of HH are known, classified by age of onset, genetic cause, clinical manifestations and mode of inheritance. Except for the rare form of juvenile haemochromatosis, symptoms do not usually appear until after decades of progressive iron loading and may be triggered by environmental and lifestyle factors. Despite the last decades discovery of genetic and phenotype diversity of HH, early studies showed a frequent involvement of the endocrine glands where diabetes and hypogonadism are the most common encountered endocrinopathies. The pathogenesis of diabetes is still relatively unclear, but the main mechanisms include the loss of insulin secretory capacity and insulin resistance secondary to liver damage. The presence of obesity and/or genetic predisposition may represent addictive risk factor for the development of this metabolic disease. Although old cases of primary gonad involvement are described, hypogonadism is mainly secondary to selective deposition of iron on the gonadotropin-producing cells of the pituitary gland, leading to hormonal impaired secretion. Cases of hypopituitarism or selected tropin defects, and abnormalities of adrenal, thyroid and parathyroid glands, even if rare, are reported. The prevalence of individual gland dysfunction varies enormously within studies for several bias due to small numbers of and selected cases analyzed, mixed genotypes and missing data on medical history. Moreover, in the last few years early screening and awareness of the disease among physicians have allowed hemochromatosis to be diagnosed in most cases at early stages when patients have no symptoms. Therefore, the clinical presentation of this disease has changed significantly and the recognized common complications are encountered less frequently. This review summarizes the current knowledge on HH-associated endocrinopathies.

A late presentation of a fatal disease: juvenile hemochromatosis

Juvenile hemochromatosis is a rare and severe form of hereditary hemochromatosis. We report the case of a 39-year-old female who presented with heart failure and cirrhosis from previously unrecognized juvenile hemochromatosis. This is the latest presentation described in the literature. An important clue to the diagnosis was a history of amenorrhea since the age of 20 that had never been investigated. The patient died of intractable heart failure two months after the initial presentation. Juvenile hemochromatosis should be suspected in a young patient with endocrine or cardiac manifestations. Early diagnosis is crucial since phlebotomy can improve the prognosis and delay or prevent progression to heart failure and cirrhosis.

Screening for hereditary haemochromatosis

Hereditary haemochromatosis (HH) is a common autosomal recessive disorder of iron overload in Caucasian populations. Clinical manifestations usually occur in individuals homozygous for the C282Y mutation in the HFE gene product and who have developed significant iron loading. Current screening methods can detect affected individuals either prior to or early during disease evolution, enabling early introduction of phlebotomy treatment that can normalise life expectancy. Evaluation of possible iron overload, via measurement of serum transferrin saturation and ferritin level, is the most appropriate initial test for those subjects presenting clinically for evaluation. HFE genotyping, when combined with serum biochemical measurements, defines the presence of likely iron overload and the underlying genetic disorder and is the preferred initial screening modality for families of an affected individual. Definitive proof of iron overload requires measurement of hepatic iron concentration or total iron burden via therapeutic phlebotomy; elevated serum ferritin level alone is not adequate. We now recognise that the natural history of HH is not as discrete as previously believed, because genetic and environmental modifiers of disease penetrance are increasingly identified as influencing the clinical expression of HH. In fact, a minority of C282Y homozygotes develop classical 'iron overload disease', although it has recently emerged that the disorder may predispose to breast and colorectal cancer. Uncertainties as to the true clinical impact of the condition at a population level lead to current recommendations of cascade screening of families of affected patients, case-finding in high-risk groups, such as patients with clinical manifestations consistent with the diagnosis, and a high level of clinical awareness in the community to facilitate early diagnosis. Generalised population screening is not presently recommended.

A comparison between whites and blacks with severe multi-organ iron overload identified in 16,152 autopsies

BACKGROUND & AIMS

Little is known about differences in the prevalence of severe iron overload at death in whites and blacks. We evaluated data and samples from 16,152 autopsies (8484 whites, 7668 blacks) performed at a single university hospital.

METHODS

Cases of severe multi-organ iron overload were identified by review of autopsy protocols and Perls-stained tissue specimens, analysis of hepatocyte and Kupffer cell iron levels, and measurement of liver tissue iron concentrations.

RESULTS

We analyzed autopsy data from 10,345 adults (age > or =21 years), 1337 children (1-20 years), and 4470 infants (<1 year). Iron overload without reports of excessive exogenous iron was observed in 18 adults; the prevalence in whites and blacks was 0.0019 and 0.0015, respectively (P = .6494). Twenty-nine adults and 2 children had iron overload with reports of excessive exogenous iron. In adults, the prevalences of iron overload with reports of excessive exogenous iron in whites and blacks were 0.0040 and 0.0013, respectively (P = .0107). Among adults, the prevalence of cirrhosis was 6-fold greater in those with iron overload. In adults with severe iron overload, 67% without reports of excessive exogenous iron and 14% with reports of excessive exogenous iron died of hepatic failure or cardiomyopathy caused by siderosis. The overall prevalence of deaths caused by severe iron overload in whites and blacks was 0.0021 and 0.0009, respectively (P = .0842).

CONCLUSIONS

The prevalence of severe iron overload without reports of excessive exogenous iron did not differ significantly between whites and blacks. The prevalence of iron overload with reports of excessive exogenous iron was greater in whites. Hepatic failure and cardiomyopathy were common causes of death in severe iron overload cases.

Early age-of-onset iron overload and homozygosity for the novel hemojuvelin mutation HJV R54X (exon 3; c.160A-->T) in an African American male of West Indies descent

An African American male of West Indies descent was diagnosed to have elevated transferrin saturation, hyperferritinemia, severe iron deposition in hepatocytes, and hepatic cirrhosis at age 4. He was treated with serial phlebotomy to maintain a normal serum ferritin concentration thereafter. We evaluated him at age 23 and confirmed that he had normal serum ferritin levels, severe iron deposition in hepatocytes, hepatic cirrhosis, and portal hypertension. He did not have endocrinopathy, cardiomyopathy, or arthropathy. He was homozygous for the novel hemojuvelin (HJV) premature stop-codon mutation R54X (exon 3; c.160A-->T). He did not have either HFE C282Y, H63D, or S65C, or deleterious coding region mutations of SLC40A1, TFR2, or HAMP. His erythrocyte measures and hemoglobin electrophoresis were consistent with alpha-thalassemia trait. We conclude that homozygosity for HJV R54X accounts for his severe, early age-of-onset hemochromatosis; his phenotype was probably modified by serial phlebotomy therapy.

A genome-wide linkage scan for iron phenotype quantitative trait loci: the HEIRS Family Study

Iron overload phenotypes in persons with and without hemochromatosis are variable. To investigate this further, probands with hemochromatosis or evidence of elevated iron stores and their family members were recruited for a genome-wide linkage scan to identify potential quantitative trait loci (QTL) that contribute to variation in transferrin saturation (TS), unsaturated iron-binding capacity (UIBC), and serum ferritin (SF). Genotyping utilized 402 microsatellite markers with average spacing of 9 cM. A total of 943 individuals, 64% Caucasian, were evaluated from 174 families. After adjusting for age, gender, and race/ethnicity, there was evidence for linkage of UIBC to chromosome 4q logarithm of the odds (LOD) = 2.08, p = 0.001) and of UIBC (LOD = 9.52), TS (LOD = 4.78), and SF (LOD = 2.75) to the chromosome 6p region containing HFE (each p < 0.0001). After adjustments for HFE genotype and other covariates, there was evidence of linkage of SF to chromosome 16p (LOD = 2.63, p = 0.0007) and of UIBC to chromosome 5q (LOD = 2.12, p = 0.002) and to chromosome 17q (LOD = 2.19, p = 0.002). We conclude that these regions should be considered for fine mapping studies to identify QTL that contribute to variation in SF and UIBC.

[Endocrine consequences of hemochromatosis]

The two most frequent endocrine complications of hemochromatosis are diabetes mellitus and hypogonadotrophic hypogonadism. Other endocrine disorders related to this disease are very rare and are described especially in the most severe and earliest posttransfusion iron overloads. Endocrine complications are evidence of advanced hemochromatosis, often already associated with cirrhosis. Given the low frequency of HFE mutations in type 2 diabetes, routine genetic testing in this population does not seem reasonable. Testing for iron overload is recommended in subjects with atypical type 2 diabetes (for example, patients who are not overweight) and in cases of hypogonadism, characteristic pigmentation, or cirrhosis. Phlebotomy plays an important role in the management of endocrine complications of hemochromatosis, especially when diagnosis is early. In all cases of hypogonadotrophic hypogonadism, primary hemochromatosis must be considered.

Compound heterozygote (C282Y/H63D) of hereditary hemochromatosis in a 16-year-old girl with hypoplastic kidney

Iron-overload diseases are associated with primary or secondary disturbances of iron metabolism. Hereditary hemochromatosis, a genetically heterogeneous disease that is characterized by increased iron absorption and progressive deposition in parenchymal cells, may lead to organ damage and failure. Molecular studies have shown that hemochromatosis type 1 is predominantly due to a mutation in the HFE gene; there are 2 major mutations (C282Y and H63D). Disease symptoms are observed mostly after 40 years of age, often in men. We report the unusual case of a 16-year-old girl with an elevated serum iron level and a hypoplastic kidney. Identification of heterozygosity for the HFE gene mutation C282Y/H63D confirmed the diagnosis of hemochromatosis type 1. The early detection of hemochromatosis in the presented case may delay organ damage and failure due to iron overload.

Reversibility of hypogonadotropic hypogonadism in a patient with the juvenile form of hemochromatosis

OBJECTIVE

To report a case of complete reversibility of hypogonadotropic hypogonadism with intensive venesection treatment in juvenile hemochromatosis.

DESIGN

Case report.

SETTING

Endocrine department of Hippocrateion Hospital of Athens.

PATIENT(S)

A 25-year-old man who presented with hypogonadotropic hypogonadism and severe iron overload due to juvenile hemochromatosis and who was initially treated with phlebotomies and androgen substitution.

INTERVENTION(S)

Intensification of chelation therapy.

MAIN OUTCOME MEASURE(S)

Clinical evaluation, serum ferritin concentration, and biochemical assessment of pituitary function were performed periodically.

RESULT(S)

One year after normalization of serum ferritin levels and transferrin saturation was achieved, he became eugonadal.

CONCLUSION(S)

We believe that hypogonadotropic hypogonadism in juvenile hemochromatosis may be reversible by a consequent venesection therapy probably because treatment was intensive and promptly introduced at a young age.

Allele frequencies of hemojuvelin gene (HJV) I222N and G320V missense mutations in white and African American subjects from the general Alabama population

Background

Homozygosity or compound heterozygosity for coding region mutations of the hemojuvelin gene (HJV) in whites is a cause of early age-of-onset iron overload (juvenile hemochromatosis), and of hemochromatosis phenotypes in some young or middle-aged adults. HJV coding region mutations have also been identified recently in African American primary iron overload and control subjects. Primary iron overload unexplained by typical hemochromatosis-associated HFE genotypes is common in white and black adults in Alabama, and HJV I222N and G320V were detected in a white Alabama juvenile hemochromatosis index patient. Thus, we estimated the frequency of the HJV missense mutations I222N and G320V in adult whites and African Americans from Alabama general population convenience samples.

Methods

We evaluated the genomic DNA of 241 Alabama white and 124 African American adults who reported no history of hemochromatosis or iron overload to detect HJV missense mutations I222N and G320V using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Analysis for HJV I222N was performed in 240 whites and 124 African Americans. Analysis for HJV G320V was performed in 241 whites and 118 African Americans.

Results

One of 240 white control subjects was heterozygous for HJV I222N; she was also heterozygous for HFE C282Y, but had normal serum iron measures and bone marrow iron stores. HJV I222N was not detected in 124 African American subjects. HJV G320V was not detected in 241 white or 118 African American subjects.

Conclusions

HJV I222N and G320V are probably uncommon causes or modifiers of primary iron overload in adult whites and African Americans in Alabama. Double heterozygosity for HJV I222N and HFE C282Y may not promote increased iron absorption.

Genetic abnormalities and juvenile hemochromatosis: mutations of the HJV gene encoding hemojuvelin

Juvenile hemochromatosis is an early-onset form of iron storage disease characterized by hypogonadotrophic hypogonadism and cardiomyopathy. Recently, the putative causative gene (LOC148738) encoding a protein designated hemojuvelin was cloned. The previously proposed designation of this gene as HFE2 is contrary to established convention, because it is not a member of the HFE family. We suggest that it be designated HJV. We sequenced this gene in members of 2 previously reported kinships that manifest typical juvenile hemochromatosis. In one kinship, 2 previously undescribed mutations of HJV were identified, c.238T>C (C80R) and c.302T>C (L101P). In the second kinship, 2 previously identified mutations, G320V and I222N, were found. These studies confirm that mutations in HJV cause juvenile hemochromatosis.

Juvenile hemochromatosis locus maps to chromosome 1q in a French Canadian population

Juvenile hemochromatosis (JH) is a rare autosomal recessive disorder that causes iron overload. In the French Canadian region of Saguenay Lac-Saint-Jean the worldwide largest cohort of JH cases has been identified. Here, we report the mapping of this large cohort of cases to the HFE2 locus on chromosome 1q. A maximum multipoint location score of 7.02 was observed with marker D1S2344. A common ancestral haplotype, showing the presence of a founder effect, was identified. The analysis of recombinants allowed us to confirm the JH candidate region.