Hereditary spherocytosis and hemochromatosis

A Rare Case of Iron Overload in Hereditary Spherocytosis: A Case Report

Hereditary spherocytosis (HS) is a hereditary hematologic disorder characterized by fragile spherical red blood cells that are susceptible to hemolysis. HS patients are often asymptomatic or present with anemia; however, serious complications of chronic hemolysis can include cholelithiasis and aplastic crisis. Splenectomy is considered the standard surgical treatment in moderate and severe forms of HS, with the main complication being a life-long risk of infection. Interestingly, our case suggests a possibility of secondary hemochromatosis as a complication of chronic hemolysis seen in HS. A vast majority of hemochromatosis patients possess a genetic predisposition, which increases their serum iron level and iron storage within the reticuloendothelial system. However, we present a case in which the genetic panel for common mutations associated with hemochromatosis resulted as negative. This case emphasizes the need for increased awareness regarding the potential development of idiopathic hemochromatosis in patients with long-standing HS, allowing for prompt intervention and preventing the associated complications.

Coinheritance of hereditary spherocytosis with haemochromatosis: next-generation sequencing reveals

We report the case of a man in his 50s with extravascular haemolysis, fluctuating indirect hyperbilirubinaemia, elevated transferrin saturation with hyperferritinaemia and normal liver enzymes. Spherocytes were detected in a blood smear and a mutation of unknown significance, c.1626+1G>A p.?, in intron 13 of the SLC4A1 gene, was identified by next-generation sequencing (NGS). The same mutation was found in his daughter, who presented with similar laboratory changes, confirming the diagnosis of hereditary spherocytosis. Abdominal MRI showed hepatosplenomegaly with hepatic iron overload. In this context of haemolysis (without anaemia) and iron overload, a diagnosis of haemochromatosis was presumed. NGS confirmed the presence of the variants p.(His63Asp) and p.(Cys282Tyr) in heterozygosity in the HFE gene. We report this case for the rarity of co-existing two haematological diseases counteracting each other.

Mild Hereditary Spherocytosis without Accompanying Hereditary Haemochromatosis: An Unrecognised Cause of Iron Overload

Hereditary spherocytosis (HS) is a common inherited haemolytic anaemia and has great variability in its presentation. Non-transfusion iron overload in HS has only been reported with co-inheritance of hereditary haemochromatosis (HHC). We present 4 unrelated patients of East Asian ethnicity with mild HS and significant non-transfusion iron overload in the absence of known disease-causing mutations in HHC genes. We hypothesise that, in patients with mild HS, life-long chronic haemolysis and erythropoietic drive may promote iron absorption. This suggests that mild HS may not be entirely benign, and that patients with mild HS should be monitored for iron overload.

Fatal Cardiac Hemochromatosis in a Patient with Hereditary Spherocytosis

A 31-year-old man was admitted to our hospital with atrial tachycardia and cardiogenic shock. He had been diagnosed with hereditary spherocytosis (HS) during childhood, but he never received any red blood cell transfusions. Right ventricular endomyocardial biopsy revealed multiple myocardial hemosiderin deposits, and he was diagnosed with cardiac hemochromatosis. In addition to the iron deposition in the heart, the loss of myocyte and severe interstitial fibrosis were present. His cardiac function did not improve even after the cardioversion for atrial tachycardia, and he suffered from recurrent heart failure. Despite intensive medical treatment for heart failure and arrhythmias in combination with iron chelation therapy, he eventually died of progressive and refractory heart failure. Hemochromatosis is a systemic disorder characterized by the excessive deposition of iron in multiple organs. The occurrence of hemochromatosis in HS is extremely rare, and previous reports have shown that the coexistence of heterozygosity for the HFE gene mutation in HS patients causes excess iron storage. The prognosis is poor due to progressive congestive heart failure and refractory arrhythmias. Here we report a rare case of fatal cardiac hemochromatosis associated with HS. The possibility of cardiac hemochromatosis needs to be considered in cases of heart failure or arrhythmia in patients with HS.

Coinheritance of hereditary spherocytosis and reversibility of cirrhosis in a young female patient with hereditary hemochromatosis

Here we report a 33-years-old woman with hereditary spherocytosis and hemochromatosis due to homozygosity for the C282Y mutation of the HFE gene. The coinheritance of both conditions led to severe iron overload and liver cirrhosis at young age. The patient was treated by repeated phlebotomy, and reversibility of cirrhosis was documented by transient elastography. This report discusses the pathophysiology of iron accumulation in patients with hemolytic anemia combined with HFE C282Y homozygosity. The case indicates that patients with hematological disorders characterized by increased erythropoetic activity should be screened for HFE mutations.

The high oxygen-affinity Hemoglobin Johnstown [(beta 109(G11) Val-->Leu] in a German kindred with an elevated erythrocyte hemoglobin content: potential interaction with HFE mutations

A 23-year-old man with an elevated blood hemoglobin was found to have hemoglobin (Hb) Johnstown, a high oxygen-affinity hemoglobin and an elevated red cell hemoglobin content. The hemoglobin mutation was present in all family members who consented to molecular investigation. No elevation of the erythropoietin level was found in the carriers. A high ferritin level was observed in one family member. When carriers of the hemoglobin mutation were analyzed for mutations in the HFE-genes (C282Y, H63D and S65C), only the individual with the high ferritin level was a compound heterozygous for the H63D/S65C genotype. This genotype normally does not confer the hemochromatosis phenotype but may contribute to iron overload when present in an individual with increased hemoglobin synthesis. The original report of this hemoglobin variant was in the United States. Additional descriptions followed from Spain and Argentina. The family in this report is the first described in Central Europe carrying the beta109 (Val-->Leu) mutation.

Iron overload and prolonged ingestion of iron supplements: clinical features and mutation analysis of hemochromatosis-associated genes in four cases

We evaluated and treated four white adults (one man, three women) who had iron overload associated with daily ingestion of iron supplements for 7, 15, 35, and 61 years, respectively. We performed HFE mutation analysis to detect C282Y, H63D, and S65C in each patient; in two patients, HFE exons were sequenced. In two patients, direct sequencing was performed to detect coding region mutations of TFR2, HAMP, FPN1, HJV, and ALAS2. Patients 1-4 ingested 153, 547, 1,341, and 4,898 g of inorganic iron as supplements. Patient 1 had hemochromatosis, HFE C282Y homozygosity, and beta-thalassemia minor. Patient 2 had spherocytosis and no HFE coding region mutations. Patient 3 had no anemia, a normal HFE genotype, and no coding region mutations in HAMP, FPN1, HJV, or ALAS2; she was heterozygous for the TFR2 coding region mutation V583I (nt 1,747 G-->A, exon 15). Patient 4 had no anemia and no coding region mutations in HFE, TFR2, HAMP, FPN1, HJV, or ALAS2. Iron removed by phlebotomy was 32.4, 10.4, 15.2, and 4.0 g, respectively. There was a positive correlation of log(10) serum ferritin and the quantity of iron removed by phlebotomy (P = 0.0371). Estimated absorption of iron from supplements in patients 1-4 was 20.9%, 1.9%, 1.1%, and 0.08%. We conclude that the clinical phenotypes and hemochromatosis genotypes of adults who develop iron overload after ingesting iron supplements over long periods are heterogeneous. Therapeutic phlebotomy is feasible and effective, and would prevent complications of iron overload.

Inherited iron loading: genetic testing in diagnosis and management

Elucidation of the molecular pathways of iron transport through cells and its control is leading to an understanding of genetic iron loading conditions. The general phenotype of haemochromatosis is iron accumulation in liver parenchymal cells, a raised serum transferrin saturation and ferritin concentration. Four types have been identified: type 1 is the common form and is an autosomal recessive disorder of low penetrance strongly associated with mutations in the HFE gene on chromosome 6(p21.3); type 2 (juvenile haemochromatosis) is autosomal recessive, of high penetrance with causative mutations identified in the HFE2 gene on chromosome 1 (q21) and the HAMP gene on chromosome 19 (q13); type 3 is also autosomal recessive with mutations in the TfR2 gene on chromosome 3 (7q22); type 4 is an autosomal dominant condition with heterozygous mutations in the ferroportin 1 gene. In type 4, iron accumulates in both parenchymal and reticuloendothelial cells and the transferrin saturation may be normal. There are also inherited neurodegenerative conditions associated with iron accumulation. The current research challenges include understanding the central role of the HAMP gene (hepcidin) in controlling iron absorption and the reasons for the variable penetrance in HFE type 1.

Congenital spherocytosis with hereditary hemochromatosis without pathogenic mutations in the HFE gene

We report a case of an 80-year-old woman with congenital spherocytosis who presented with massive iron overload. Iatrogenic iron overload could be ruled out. Familial history was suggestive of hereditary hemochromatosis; however, molecular genetic testing for the most common HFE mutations remained negative. The patient was treated successfully with phlebotomies. The hypothesis that this patient suffered from hereditary hemochromatosis is discussed on the basis of a brief review of the literature.

Prevalence of HFE mutations among the Thai population and correlation with iron loading in haemoglobin E disorder*

Co-inheritance of HFE mutations has a substantial role in iron overload in beta-thalassaemia carriers in north European populations where two HFE mutations, C282Y and H63D, are prevalent. In Thailand, there was little information about the allele frequency of HFE mutations. It is of interest to determine whether such determinants represent a potential risk in developing iron overload as nearly 40% of the Thai population carry either one of thalassaemia or haemoglobinpathy alleles. A total of 380 normal controls from five different regions including Bangkok were screened for the HFE C282Y, H63D and IVS5+1 G-->A alleles. In addition, 70 individuals with homozygous haemoglobin E (Hb EE) were also tested and their genotypes were correlated with levels of serum ferritin. H63D is the major HFE mutation found in the Thai population with an average allele frequency of 3% (range 1-5%). One individual was heterozygous for the splice site mutation IVS5 + 1 G --> A, and the C282Y allele was not detected. In the Hb EE group, five individuals had iron deficiency (ferritin <12 microg/L) and the remaining 65 individuals had a wide range of serum ferritin levels of 16-700 microg/L. Four individuals with Hb EE were heterozygous for the H63D allele. No significant difference in serum ferritin level was detected in this group with or without the HFE mutation (137.2 +/- 78 vs. 116.3 +/- 128 microg/L). HFE mutations are relatively uncommon among the Thai population, and the average allele frequency of the ancient H63D mutation is similar to that of other countries in this region. Because of their paucity, it appears that these alleles are less likely to be responsible for high ferritin levels and iron loading in individuals with Hb E related disorders.

Iron Deficiency and Overload

In the past seven years numerous genes that influence iron homeostasis have been discovered. Dr. Beutler provides a brief overview of these genes, genes that encode HFE, DMT-1, ferroportin, transferrin receptor 2, hephaestin, and hepcidin to lay the groundwork for a discussion of the various clinical forms of iron storage disease and how they differ from one another.

In Section I, Dr. Beutler also discusses the types of hemochromatosis that exist as acquired and as hereditary forms. Acquired hemochromatosis occurs in patients with marrow failure, particularly when there is active ineffective erythropoiesis. Hereditary hemochromatosis is most commonly due to mutations in the HLA-linked HFE gene, and hemochromatosis clinically indistinguishable from HFE hemochromatosis is the consequence of mutations in three transferrin receptor-2 gene. A more severe, juvenile form of iron storage disease results from mutations of the gene encoding hepcidin or of a not-yet-identified gene on chromosome 1q. Autosomal dominant iron storage disease is a consequence of ferroportin mutations, and a polymorphism in the ferroportin gene appears to be involved in the African iron overload syndrome.

Evidence regarding the biochemical and clinical penetrance of hemochromatosis due to mutations of the HFE gene is rapidly accumulating. These studies, emanating from several centers in Europe and the United States, all agree that the penetrance of hemochromatosis is much lower than had previously been thought. Probably only 1% of homozygotes develop clinical findings. The implications of these new findings for the management of hemochromatosis will be discussed.

In Section II, Dr. Victor Hoffbrand discusses the management of iron storage disease by chelation therapy, treatment that is usually reserved for patients with secondary hemochromatosis such as occurs in the thalassemias and in patients with transfusion requirements due to myelodysplasia and other marrow failure states. Tissue iron can be estimated by determining serum ferritin levels, measuring liver iron, and by measuring cardiac iron using the MRI-T2* technique. The standard form of chelation therapy is the slow intravenous or subcutaneous infusion of desferoxamine. An orally active bidentate iron chelator, deferiprone, is now licensed in 25 countries for treatment of patients with thalassemia major. Possibly because of the ability of this compound to cross membranes, it appears to have superior cardioprotective properties. Agranulocytosis is the most serious complication of deferiprone therapy and occurs in about 1% of treated patients. Deferiprone and desferoxamine can be given together or on alternating schedules. A new orally active chelating agent ICL 670 seems promising in early clinical studies.

In Section III, Dr. James Cook discusses the most common disorder of iron homeostasis, iron deficiency. He will compare some of the standard methods for identifying iron deficiency, the hemoglobin level, transferrin saturation, and mean corpuscular hemoglobin and compare these with some of the newer methods that have been introduced, specifically the percentage of hypochromic erythrocytes and reticulocyte hemoglobin content. The measurement of storage iron is achieved by measuring serum ferritin levels. The soluble transferrin receptor is a truncated form of the cellular transferrin receptor and the possible value of this measurement in the diagnosis of iron deficiency will be discussed. Until recently iron dextran was the only parental iron preparation available in the US. Sodium ferric gluconate, which has been used extensively in Europe for many years, is now available in the United States. It seems to have a distinct advantage over iron dextran in that anaphylactic reactions are much less common with the latter preparation.