RESUMO
The congenital sideroblastic anemias (CSAs) are a heterogeneous group of inherited disorders of erythropoiesis characterized by pathologic deposits of iron in the mitochondria of developing erythroblasts. Mutations in the mitochondrial glycine carrier SLC25A38 cause the most common recessive form of CSA. Nonetheless, the disease is still rare, there being fewer than 70 reported families. Here we describe the clinical phenotype and genotypes of 31 individuals from 24 families, including 11 novel mutations. We also review the spectrum of reported mutations and genotypes associated with the disease, describe the unique localization of missense mutations in transmembrane domains and account for the presence of several alleles in different populations.
Assuntos
Anemia Sideroblástica/congênito , Genótipo , Proteínas de Transporte da Membrana Mitocondrial/genética , Mutação , Fenótipo , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , MasculinoRESUMO
The congenital sideroblastic anemias (CSAs) can be caused by primary defects in mitochondrial iron-sulfur (Fe-S) cluster biogenesis. HSCB (heat shock cognate B), which encodes a mitochondrial cochaperone, also known as HSC20 (heat shock cognate protein 20), is the partner of mitochondrial heat shock protein A9 (HSPA9). Together with glutaredoxin 5 (GLRX5), HSCB and HSPA9 facilitate the transfer of nascent 2-iron, 2-sulfur clusters to recipient mitochondrial proteins. Mutations in both HSPA9 and GLRX5 have previously been associated with CSA. Therefore, we hypothesized that mutations in HSCB could also cause CSA. We screened patients with genetically undefined CSA and identified a frameshift mutation and a rare promoter variant in HSCB in a female patient with non-syndromic CSA. We found that HSCB expression was decreased in patient-derived fibroblasts and K562 erythroleukemia cells engineered to have the patient-specific promoter variant. Furthermore, gene knockdown and deletion experiments performed in K562 cells, zebrafish, and mice demonstrate that loss of HSCB results in impaired Fe-S cluster biogenesis, a defect in RBC hemoglobinization, and the development of siderocytes and more broadly perturbs hematopoiesis in vivo. These results further affirm the involvement of Fe-S cluster biogenesis in erythropoiesis and hematopoiesis and define HSCB as a CSA gene.
Assuntos
Anemia Sideroblástica/genética , Chaperonas Moleculares/genética , Mutação , Adolescente , Anemia Sideroblástica/congênito , Anemia Sideroblástica/metabolismo , Animais , Criança , Análise Mutacional de DNA , Feminino , Mutação da Fase de Leitura , Técnicas de Silenciamento de Genes , Humanos , Proteínas Ferro-Enxofre/deficiência , Proteínas Ferro-Enxofre/genética , Células K562 , Masculino , Camundongos , Camundongos Knockout , Chaperonas Moleculares/metabolismo , Linhagem , Polimorfismo de Nucleotídeo Único , Regiões Promotoras Genéticas , Adulto Jovem , Peixe-ZebraRESUMO
The case of an infant girl with severe congenital sideroblastic anemia associated with a novel molecular defect in mitochondrial transporter SLC25A38 is presented. Her transfusion dependence was fully reversed following allogeneic hematopoietic stem cell transplantation using a modified reduced-intensity conditioning regimen, and she remains healthy 5 years posttransplant.
RESUMO
YARS2 variants have previously been described in patients with myopathy, lactic acidosis and sideroblastic anemia 2 (MLASA2). YARS2 encodes the mitochondrial tyrosyl-tRNA synthetase, which is responsible for conjugating tyrosine to its cognate mt-tRNA for mitochondrial protein synthesis. Here we describe 14 individuals from 11 families presenting with sideroblastic anemia and YARS2 variants that we identified using a sideroblastic anemia gene panel or exome sequencing. The phenotype of these patients ranged from MLASA to isolated congenital sideroblastic anemia. As in previous cases, inter- and intra-familial phenotypic variability was observed, however, this report includes the first cases with isolated sideroblastic anemia and patients with biallelic YARS2 variants that have no clinically ascertainable phenotype. We identified ten novel YARS2 variants and three previously reported variants. In vitro amino-acylation assays of five novel missense variants showed that three had less effect on the catalytic activity of YARS2 than the most commonly reported variant, p.(Phe52Leu), associated with MLASA2, which may explain the milder phenotypes in patients with these variants. However, the other two missense variants had a more severe effect on YARS2 catalytic efficiency. Several patients carried the common YARS2 c.572 G>T, p.(Gly191Val) variant (minor allele frequency =0.1259) in trans with a rare deleterious YARS2 variant. We have previously shown that the p.(Gly191Val) variant reduces YARS2 catalytic activity. Consequently, we suggest that biallelic YARS2 variants, including severe loss-of-function alleles in trans of the common p.(Gly191Val) variant, should be considered as a cause of isolated congenital sideroblastic anemia, as well as the MLASA syndromic phenotype.
Assuntos
Acidose Láctica/genética , Anemia Sideroblástica/genética , Doenças Genéticas Ligadas ao Cromossomo X/genética , Mutação em Linhagem Germinativa , Síndrome MELAS/genética , Proteínas Mitocondriais/genética , Tirosina-tRNA Ligase/genética , Acidose Láctica/enzimologia , Adolescente , Anemia Sideroblástica/enzimologia , Feminino , Estudos de Associação Genética , Doenças Genéticas Ligadas ao Cromossomo X/enzimologia , Humanos , Lactente , Síndrome MELAS/enzimologia , Masculino , Pessoa de Meia-Idade , Mutação de Sentido Incorreto , Adulto JovemAssuntos
Anemia Sideroblástica/genética , DNA Mitocondrial/genética , Doenças Genéticas Ligadas ao Cromossomo X/genética , ATPases Mitocondriais Próton-Translocadoras/genética , Mutação de Sentido Incorreto , Adolescente , Anemia Sideroblástica/metabolismo , Anemia Sideroblástica/patologia , Criança , Análise Mutacional de DNA/métodos , Feminino , Estudos de Associação Genética , Doenças Genéticas Ligadas ao Cromossomo X/metabolismo , Doenças Genéticas Ligadas ao Cromossomo X/patologia , Humanos , Lactente , Masculino , ATPases Mitocondriais Próton-Translocadoras/metabolismo , Mutação Puntual , Recidiva , SíndromeRESUMO
The congenital sideroblastic anemias (CSAs) are a heterogeneous group of inherited blood disorders characterized by pathological mitochondrial iron deposition in erythroid precursors. Each known cause has been attributed to a mutation in a protein associated with heme biosynthesis, iron-sulfur cluster biogenesis, mitochondrial translation, or a component of the mitochondrial respiratory chain. Here, we describe a recurring mutation, c.276_278del, p.F93del, in NDUFB11, a mitochondrial respiratory complex I-associated protein encoded on the X chromosome, in 5 males with a variably syndromic, normocytic CSA. The p.F93del mutation results in respiratory insufficiency and loss of complex I stability and activity in patient-derived fibroblasts. Targeted introduction of this allele into K562 erythroleukemia cells results in a proliferation defect with minimal effect on erythroid differentiation potential, suggesting the mechanism of anemia in this disorder.
Assuntos
Anemia Sideroblástica/genética , Sequência de Bases , Cromossomos Humanos X/genética , Complexo I de Transporte de Elétrons/genética , Doenças Genéticas Ligadas ao Cromossomo X/genética , Deleção de Sequência , Adolescente , Adulto , Idoso , Anemia Sideroblástica/metabolismo , Anemia Sideroblástica/patologia , Criança , Pré-Escolar , Cromossomos Humanos X/metabolismo , Complexo I de Transporte de Elétrons/metabolismo , Feminino , Doenças Genéticas Ligadas ao Cromossomo X/metabolismo , Humanos , Células K562 , Masculino , Pessoa de Meia-IdadeRESUMO
The congenital sideroblastic anemias (CSAs) are relatively uncommon diseases characterized by defects in mitochondrial heme synthesis, iron-sulfur (Fe-S) cluster biogenesis, or protein synthesis. Here we demonstrate that mutations in HSPA9, a mitochondrial HSP70 homolog located in the chromosome 5q deletion syndrome 5q33 critical deletion interval and involved in mitochondrial Fe-S biogenesis, result in CSA inherited as an autosomal recessive trait. In a fraction of patients with just 1 severe loss-of-function allele, expression of the clinical phenotype is associated with a common coding single nucleotide polymorphism in trans that correlates with reduced messenger RNA expression and results in a pseudodominant pattern of inheritance.
Assuntos
Anemia Sideroblástica/genética , Doenças Genéticas Ligadas ao Cromossomo X/genética , Proteínas de Choque Térmico HSP70/genética , Proteínas Mitocondriais/genética , Adulto , Idoso , Sequência de Bases , Análise Mutacional de DNA , Feminino , Genótipo , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Mutação , Análise de Sequência com Séries de Oligonucleotídeos , Linhagem , Polimorfismo de Nucleotídeo Único , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Adulto JovemRESUMO
Mutations in genes encoding proteins that are involved in mitochondrial heme synthesis, iron-sulfur cluster biogenesis, and mitochondrial protein synthesis have previously been implicated in the pathogenesis of the congenital sideroblastic anemias (CSAs). We recently described a syndromic form of CSA associated with B-cell immunodeficiency, periodic fevers, and developmental delay (SIFD). Here we demonstrate that SIFD is caused by biallelic mutations in TRNT1, the gene encoding the CCA-adding enzyme essential for maturation of both nuclear and mitochondrial transfer RNAs. Using budding yeast lacking the TRNT1 homolog, CCA1, we confirm that the patient-associated TRNT1 mutations result in partial loss of function of TRNT1 and lead to metabolic defects in both the mitochondria and cytosol, which can account for the phenotypic pleiotropy.
Assuntos
Anemia Sideroblástica/congênito , Anemia Sideroblástica/genética , Deficiências do Desenvolvimento/complicações , Febre/complicações , Doenças Genéticas Ligadas ao Cromossomo X/genética , Síndromes de Imunodeficiência/complicações , Mutação/genética , RNA Nucleotidiltransferases/genética , Alelos , Anemia Sideroblástica/complicações , Anemia Sideroblástica/enzimologia , Deficiências do Desenvolvimento/genética , Febre/genética , Doenças Genéticas Ligadas ao Cromossomo X/complicações , Doenças Genéticas Ligadas ao Cromossomo X/enzimologia , Células HEK293 , Humanos , Síndromes de Imunodeficiência/genéticaRESUMO
Sideroblastic anemias (SAs) may be acquired or congenital and share the features of disrupted utilization of iron in the erythroblast, ineffective erythropoiesis, and variable systemic iron overload. Congenital forms can have associated syndromic features or be nonsyndromic, and many of them have mutations in genes encoding proteins involved in heme biosynthesis, iron-sulfur cluster biogenesis, or mitochondrial protein synthesis. The mechanism(s) for the acquired clonal SA is undefined and is under intense study. Precise diagnosis of these disorders rests on careful clinical and laboratory evaluation, including molecular analysis. Supportive treatments usually provide for a favorable prognosis and often for normal survival.
Assuntos
Anemia Sideroblástica/diagnóstico , Anemia Sideroblástica/terapia , Anemia Sideroblástica/complicações , Gerenciamento Clínico , Humanos , Sobrecarga de Ferro/etiologiaRESUMO
X-linked sideroblastic anemia (XLSA) is the most common form of congenital sideroblastic anemia. In affected males, it is uniformly associated with partial loss-of-function missense mutations in the erythroid-specific heme biosynthesis protein 5-aminolevulinate synthase 2 (ALAS2). Here, we report five families with XLSA owing to mutations in a GATA transcription factor binding site located in a transcriptional enhancer element in intron 1 of the ALAS2 gene. As such, this study defines a new class of mutations that should be evaluated in patients undergoing genetic testing for a suspected diagnosis of XLSA.
Assuntos
5-Aminolevulinato Sintetase/genética , Anemia Sideroblástica/genética , Elementos Facilitadores Genéticos/genética , Fatores de Transcrição GATA/metabolismo , Doenças Genéticas Ligadas ao Cromossomo X/genética , Íntrons/genética , Mutação , Adulto , Idoso , Anemia Sideroblástica/sangue , Sítios de Ligação , Europa (Continente)/etnologia , Feminino , Doenças Genéticas Ligadas ao Cromossomo X/sangue , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Linhagem , Adulto JovemRESUMO
Congenital sideroblastic anemias (CSAs) are a heterogeneous group of inherited disorders identified by pathological erythroid precursors with perinuclear mitochondrial iron deposition in bone marrow. An international collaborative group of physicians and laboratory scientists collated clinical information on cases of CSA lacking known causative mutations, identifying a clinical subgroup of CSA associated with B immunodeficiency, periodic fevers, and development delay. Twelve cases from 10 families were identified. Median age at presentation was 2 months. Anemia at diagnosis was sideroblastic, typically severe (median hemoglobin, 7.1 g/dL) and markedly microcytic (median mean corpuscular volume, 62.0 fL). Clinical course involved recurrent febrile illness and gastrointestinal disturbance, lacking an infective cause. Investigation revealed B-cell lymphopenia (CD19⺠range, 0.016-0.22 × 109/L) and panhypogammaglobulinemia in most cases. Children displayed developmental delay alongside variable neurodegeneration, seizures, cerebellar abnormalities, sensorineural deafness, and other multisystem features. Most required regular blood transfusion, iron chelation, and intravenous immunoglobulin replacement. Median survival was 48 months, with 7 deaths caused by cardiac or multiorgan failure. One child underwent bone marrow transplantation aged 9 months, with apparent cure of the hematologic and immunologic manifestations. We describe and define a novel CSA and B-cell immunodeficiency syndrome with additional features resembling a mitochondrial cytopathy. The molecular etiology is under investigation.
Assuntos
Anemia Sideroblástica/diagnóstico , Linfócitos B/imunologia , Deficiências do Desenvolvimento/diagnóstico , Febre Familiar do Mediterrâneo/diagnóstico , Síndromes de Imunodeficiência/diagnóstico , Anemia Sideroblástica/sangue , Anemia Sideroblástica/genética , Deficiências do Desenvolvimento/sangue , Deficiências do Desenvolvimento/genética , Febre Familiar do Mediterrâneo/sangue , Febre Familiar do Mediterrâneo/genética , Feminino , Perda Auditiva Neurossensorial/sangue , Perda Auditiva Neurossensorial/diagnóstico , Perda Auditiva Neurossensorial/genética , Humanos , Síndromes de Imunodeficiência/sangue , Síndromes de Imunodeficiência/genética , Lactente , Recém-Nascido , Masculino , Doenças do Sistema Nervoso/sangue , Doenças do Sistema Nervoso/diagnóstico , Doenças do Sistema Nervoso/genética , Linhagem , Fenótipo , SíndromeAssuntos
5-Aminolevulinato Sintetase/genética , Substituição de Aminoácidos , Anemia Sideroblástica/genética , Sobrecarga de Ferro/genética , Adulto , Negro ou Afro-Americano , Anemia Sideroblástica/etnologia , Criança , Estudos de Associação Genética , Doenças Genéticas Ligadas ao Cromossomo X , Humanos , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Índice de Gravidade de Doença , Estados UnidosRESUMO
BACKGROUND: Sideroblastic anemias are heterogeneous congenital and acquired bone marrow disorders characterized by pathologic iron deposits in mitochondria of erythroid precursors. Among the congenital sideroblastic anemias (CSAs), the most common form is X-linked sideroblastic anemia, due to mutations in 5-aminolevulinate synthase (ALAS2). A novel autosomal recessive CSA, caused by mutations in the erythroid specific mitochondrial transporter SLC25A38, was recently defined. Other known etiologies include mutations in genes encoding the thiamine transporter SLC19A2, the RNA-modifying enzyme pseudouridine synthase 1 (PUS1), a mitochondrial ATP-binding cassette transporter (ABCB7), glutaredoxin 5 (GLRX5), as well as mitochondrial DNA deletions. Despite these known diverse causes, in a substantial portion of CSA cases a presumed genetic defect remains unknown. PROCEDURE: In the context of the recent discovery of SLC25A38 as a major novel cause, we systematically analyzed a large cohort of previously unreported CSA patients. Sixty CSA probands (28 females, 32 males) were examined for ALAS2, SLC25A38, PUS1, GLRX5, and ABCB7 mutations. SLC19A2 and mitochondrial DNA were only analyzed if characteristic syndromic features were apparent. RESULTS: Twelve probands had biallelic mutations in SLC25A38. Seven ALAS2 mutations were detected in eight sporadic CSA cases, two being novel. We also identified a novel homozygous null PUS1 mutation and novel mitochondrial DNA deletions in two patients with Pearson syndrome. No mutations were encountered in GLRX5, ABCB7, or SLC19A2. CONCLUSIONS: The remaining undefined probands (43%) can be grouped according to gender, family, and clinical characteristics, suggesting novel X-linked and autosomal recessive forms of CSA.
Assuntos
Anemia Sideroblástica/epidemiologia , Anemia Sideroblástica/genética , Heterogeneidade Genética , Mutação , 5-Aminolevulinato Sintetase/genética , Transportadores de Cassetes de Ligação de ATP/genética , Adolescente , Adulto , Anemia Sideroblástica/congênito , Criança , Pré-Escolar , Feminino , Glutarredoxinas/genética , Humanos , Hidroliases/genética , Lactente , Masculino , Proteínas de Membrana Transportadoras/genética , Pessoa de Meia-Idade , Proteínas de Transporte da Membrana Mitocondrial/genética , Estados Unidos/epidemiologiaRESUMO
The sideroblastic anemias are a heterogeneous group of congenital and acquired hematological disorders whose morphological hallmark is the presence of ringed sideroblasts--bone marrow erythroid precursors containing pathologic iron deposits within mitochondria. Here, by positional cloning, we define a previously unknown form of autosomal recessive nonsyndromic congenital sideroblastic anemia, associated with mutations in the gene encoding the erythroid specific mitochondrial carrier family protein SLC25A38, and demonstrate that SLC25A38 is important for the biosynthesis of heme in eukaryotes.
Assuntos
Anemia Sideroblástica/genética , Proteínas de Transporte da Membrana Mitocondrial/genética , Mutação , Animais , Portador Sadio , Família , Peixes/genética , Heme/biossíntese , Humanos , Fenótipo , Leveduras/genéticaRESUMO
BACKGROUND: : Acquired copper deficiency in adults leads to hematological and neurological manifestations that mimic vitamin B12 deficiency. A significant number of patients with copper deficiency syndrome have a history of gastric surgery, often remote. We sought to determine whether copper deficiency is present in a population of individuals with longstanding partial gastric resection. METHODS: : Serum copper, ceruloplasmin, and zinc levels were determined in 20 patients with a history of partial gastric resection and 50 controls, randomly selected from the Oklahoma City Veterans Affairs Medical Center electronic database. RESULTS: : Hypocupremia and symptoms of copper deficiency were detected in patients with partial gastric resection in contrast to controls (3/20 versus 0/50, P = 0.02). Serum copper and ceruloplasmin levels were significantly lower in individuals with partial gastric resection than in controls (P = 0.04 and P = 0.001, respectively). The mean interval between gastric surgery and testing was 20.7 years. CONCLUSIONS: : Our results indicate that a significant number of individuals with longstanding history of partial gastric resection have undiagnosed hypocupremia. Screening for copper deficiency after gastric surgery may prevent the development of hematological and neurological complications in these patients.
Assuntos
Cobre/deficiência , Gastrectomia/efeitos adversos , Complicações Pós-Operatórias/sangue , Adulto , Idoso , Idoso de 80 Anos ou mais , Ceruloplasmina/metabolismo , Cobre/administração & dosagem , Suplementos Nutricionais , Humanos , Masculino , Pessoa de Meia-Idade , Deficiência de Vitamina B 12/sangueAssuntos
Confusão/etiologia , Porfirias/diagnóstico , Acidose Láctica/etiologia , Doença Aguda , Anticonvulsivantes/administração & dosagem , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Diagnóstico Diferencial , Dieta Redutora , Combinação de Medicamentos , Eletroencefalografia , Epilepsia Tônico-Clônica/líquido cefalorraquidiano , Epilepsia Tônico-Clônica/tratamento farmacológico , Epilepsia Tônico-Clônica/etiologia , Estrogênios Conjugados (USP) , Evolução Fatal , Feminino , Cefaleia/etiologia , Terapia de Reposição Hormonal , Humanos , Imageamento por Ressonância Magnética , Acetato de Medroxiprogesterona , Pessoa de Meia-Idade , Fenobarbital/administração & dosagem , Fenitoína/administração & dosagem , Porfirias/complicações , Porfirias/urina , Punção Espinal , Tomografia Computadorizada por Raios X , Ácido Valproico/administração & dosagem , Vômito/etiologia , Redução de PesoRESUMO
OBJECTIVE: To determine the frequency and spectrum of somatic mutations of mitochondrial DNA (mtDNA) in bone marrow of patients with myelodysplastic syndrome (MDS). MATERIALS AND METHODS: Analysis included 104 patients with MDS (24 refractory anemia, 32 refractory anemia with ringed sideroblasts, 34 refractory anemia with excess of blasts, 7 refractory anemia with excess of blasts in transformation to acute leukemia, and 7 chronic myelo-monocytic leukemia), 3 patients with acute myeloid leukemia from MDS, and 36 patients with myeloproliferative disease (23 chronic myeloid leukemia, 9 polycythemia vera, 4 idiopathic myelofibrosis). Mutation scanning was performed using heteroduplex analysis with denaturing high-performance liquid chromatography (dHPLC). The entire mitochondrial genome was amplified in 67 overlapping polymerase chain reaction fragments carefully optimized regarding DNA melting profiles. Abnormal dHPLC findings were confirmed by DNA sequencing. RESULTS: Heteroplasmic mtDNA mutations, mostly transitions, were identified in 56% of MDS and 44% of myeloproliferative disorders patients. In MDS, mutation frequency increased with age and more-advanced disease. Mutational spectra showed no hot spots and were similar in different types of MDS. Heteroplasmic mutations generally did not represent known polymorphisms, and about half of them affected conserved amino acids or nucleotides. Mutations were less frequent in protein encoding genes (50 per 10(6) base pairs) than other mitochondrial genes (transfer RNAs, ribosomal RNAs, and control region; about 80 per 10(6) base pairs). CONCLUSIONS: As mitochondria often show ultrastructural abnormalities in MDS, including pathological iron accumulation, mitochondrial dysfunction may contribute to MDS pathology. We found a high frequency of acquired mtDNA mutations in MDS. However, their functional importance remains unclear, considering that genotype correlates poorly with phenotype in mitochondrial diseases. The clonally expanded mtDNA mutations in MDS support the concept of age-related damage to mtDNA in hematopoietic stem cells.
Assuntos
DNA Mitocondrial/genética , Síndromes Mielodisplásicas/genética , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Medula Óssea/patologia , Cromatografia Líquida de Alta Pressão/métodos , Análise Mutacional de DNA , Progressão da Doença , Humanos , Pessoa de Meia-Idade , Mutação , Reação em Cadeia da Polimerase/métodos , Sensibilidade e EspecificidadeRESUMO
Clinical similarities between vitamin B(12) and copper deficiencies prompted us to investigate if hypocupremia is present in patients receiving vitamin B(12) supplementation. Our pilot study results indicate that a significant number of elderly patients with prior diagnosis of vitamin B(12) deficiency have also undiagnosed hypocupremia.
Assuntos
Ceruloplasmina/análise , Cobre/deficiência , Doenças Neurodegenerativas/sangue , Deficiência de Vitamina B 12 , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doenças Neurodegenerativas/etiologia , Projetos Piloto , Vitamina B 12/sangue , Deficiência de Vitamina B 12/sangue , Deficiência de Vitamina B 12/complicaçõesRESUMO
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.