Congenital dyserythropoietic anemia types Ib, II, and III: novel variants in the CDIN1 gene and functional study of a novel variant in the KIF23 gene.

Congenital dyserythropoietic anemias (CDA) are disorders characterized by ineffective erythropoiesis and morphological anomalies in erythrocytes and erythroblasts. The purpose of this study is to identify the gene variants in patients diagnosed with CDA. We analyzed five unrelated patients and two siblings with a targeted panel of genes to CDA: CDAN1, CDIN1, SEC23B, KIF23, KLF1, and GATA1 genes. We found three novel variants in the CDIN1 gene (p.Leu136Val, p.Tyr247Cys, and p.Ile273Thr), four known variants in the SEC23B gene (p.Arg14Trp, p.Arg554Ter, p.Asp239Gly, and p.Ser436Leu), and one novel variant in the KIF23 gene (p.Leu945Trpfs*31). The in silico analysis of novel variants predict that they are pathogenic and, the in vitro study confirms the functional impact of the KIF23 variant on the protein location.

Clinical and genetic features of congenital dyserythropoietic anemia (CDA).

INTRODUCTION: Congenital dyserythropoietic anemias (CDA) are characterized by hyporegenerative anemia with inadequate reticulocyte values, ineffective erythropoiesis, and hemolysis. Distinctive morphology of bone marrow erythroblasts and identification of causative genes allow classification into 4 types caused by variants in CDAN1, c15orf41, SEC23B, KIF23, and KLF1 genes. OBJECTIVE: Identify pathogenic variants in CDA patients. METHODS: Massive parallel sequencing with a targeted gene panel, Sanger sequencing, Comparative Genome Hybridization (CGH), and in silico predictive analysis of pathogenicity. RESULTS: Pathogenic variants were found in 21 of 53 patients studied from 44 unrelated families. Six variants were found in CDAN1: two reported, p.Arg714Trp and p.Arg725Trp and, four novel, p.Arg623Trp, p.Arg946Trp, p.Phe1125Ser and p.Ser1227Gly. Twelve variants were found in SEC23B: seven reported, p.Arg14Trp, p.Glu109Lys, p.Arg217Ter, c.835-2A>G, p.Arg535Ter, p.Arg550Ter and p.Arg718Ter and, five novel, p.Val164Leu, p.Arg190Gln, p.Gln521Ter, p.Arg546Trp, and p.Arg611Gln. The variant p.Glu325Lys in KLF1 was found in one patient and p.Tyr365Cys in ALAS2 in an other. Moreover, we identified genomic rearrangements by CGH in some SEC23B-monoallelic patients. CONCLUSIONS: New technologies for genetic studies will help to find variants in other genes, in addition to those known, that contribute to or modulate the CDA phenotype or support the correct diagnosis.

A novel mutation in the SLC40A1 gene associated with reduced iron export in vitro.

Ferroportin disease is an inherited disorder of iron metabolism and is caused by mutations in the ferroportin gene (SLC40A1). We present a patient with hyperferritinemia, iron overload in the liver with reticuloendothelial distribution and also in the spleen, and under treatment with erythropheresis. A molecular study of the genes involved in iron metabolism (HFE, HJV, HAMP, TFR2, SLC40A1) was undertaken. In vitro functional studies of the novel mutation found in the SLC40A1 gene was performed. The patient was heterozygous for a novel mutation, c.386T>C (p.L129P) in the SLC40A1 gene; some of his relatives were also heterozygous for this mutation. In vitro functional studies of the L129P mutation on ferroportin showed it impairs its capacity to export iron from cells but does not alter its sensitivity to hepcidin. These findings and the iron overload phenotype of the patient suggest that the novel mutation c.386T>C (p.L129P) in the SLC40A1 gene has incomplete penetrance and causes the classical form of ferroportin disease.

Juvenile Hemochromatosis due to a Homozygous Variant in the HJV Gene.

Hemochromatosis type 2 or juvenile hemochromatosis has an early onset of severe iron overload resulting in organ manifestation such as liver fibrosis, cirrhosis, cardiomyopathy, arthropathy, hypogonadism, diabetes, osteopathic medicine, and thyroid abnormality, before age of 30. Juvenile hemochromatosis type 2a and 2b is an autosomal recessive disease caused by pathogenic variants in HJV and HAMP genes, respectively. We report a child with hepatic iron overload and family history of hemochromatosis. We aim to raise awareness of juvenile hemochromatosis, especially in families with a positive family history, as early diagnosis and treatment may prevent organ involvement and end-stage disease. The purpose of this study was to identify the gene variant that causes the disease. The genetic study was performed with a targeted gene panel: HFE, HJV, HAMP, TFR2, SLC40A1, FTL, and FTH1. We identified the variant c.309C > G (p.Phe103Leu) in the HJV gene in the homozygous state in the patient.

Two novel mutations in the SLC40A1 and HFE genes implicated in iron overload in a Spanish man.

The most common form of hemochromatosis is caused by mutations in the HFE gene. Rare forms of the disease are caused by mutations in other genes. We present a patient with hyperferritinemia and iron overload, and facial flushing. Magnetic resonance imaging was performed to measure hepatic iron overload, and a molecular study of the genes involved in iron metabolism was undertaken. The iron overload was similar to that observed in HFE hemochromatosis, and the patient was double heterozygous for two novel mutations, c.-20G>A and c.718A>G (p.K240E), in the HFE and ferroportin (FPN1 or SLC40A1) genes, respectively. Hyperferritinemia and facial flushing improved after phlebotomy. Two of the patient's children were also studied, and the daughter was heterozygous for the mutation in the SLC40A1 gene, although she did not have hyperferritinemia. The patient presented a mild iron overload phenotype probably because of the two novel mutations in the HFE and SLC40A1 genes.

Hepcidin treatment in Hfe-/- mice diminishes plasma iron without affecting erythropoiesis.

BACKGROUND: Iron is essential for mammalian metabolism and its cellular concentration is controlled by regulating its acquisition and storage. Haemochromatosis is a condition involving iron overload that is characterised by increased duodenal iron absorption and a progressive accumulation of iron in vital organs. Hepcidin is the main hormone that regulates iron homoestasis and it is secreted by the liver. MATERIALS AND METHODS: We have studied how extended hepcidin administration affects the iron load status, plasma and tissue iron concentration, erythropoiesis and the expression of proteins involved on iron homeostasis in haemochromatotic (Hfe(-/-)) and wild-type mice. RESULTS: Hepcidin reverted the high plasma iron concentrations in Hfe(-/-) mice to normal values. The high concentration of hepatic iron was not altered in the liver of these Hfe(-/-) mice. Hepcidin administration did not disturb erythropoiesis in either Hfe(-/-) or wild-type mice and likewise, hepcidin did not modify the expression of any protein analysed in the liver, duodenum or spleen of Hfe(-/-) and wild-type mice. These data confirm that hepcidin administration diminishes plasma iron concentrations. CONCLUSION: Treatment with sustained doses of hepcidin diminishes plasma iron concentrations in Hfe(-/-) mice.

The hereditary hyperferritinemia-cataract syndrome: a family study.

Ferritin is an acute-phase reactant that is elevated in the course of infectious, inflammatory, autoimmune, and oncological diseases and the hemophagocytic syndrome. In asymptomatic patients, isolated hyperferritinemia may be due to different causes depending on whether or not it is accompanied by iron overload. Hyperferritinemia values above 300 ng/ml and an excess of body iron levels may be indicative of hemochromatosis. However, if such values develop in the absence of iron overload, they may be secondary to hemochromatosis type 4a (ferroportin disease) or more often to hereditary hyperferritinemia-cataract syndrome (HHCS; Aguilar-Martinez et al., Am J Gastroenterol 100:1185-1194, 2005; Ferrante et al., Eur J Gastroenterol Hepatol 17:1247-1253, 2005). HHCS results from different mutations in the L-ferritin gene (FTL) on chromosome 19 (19q13.1), causing autosomal dominant transmission (Bertola et al., Curr Drug Targets Immune Endocr Metabol Disord 4:93-105, 2004). We present a child with HHCS due to the allelic variant c.-167C>T (C33T) in the iron-responsive element region of the FTL gene. When pediatricians encounter an asymptomatic patient with isolated hyperferritinemia in the absence of iron overload, they should consider the possibility of HHCS, especially if other members of the family have developed cataracts from a young age.

A case of congenital dyserythropoietic anemia type IV.

Congenital dyserythropoietic anemias (CDAs) are displayed by ineffective erythropoiesis. The wide variety of phenotypes observed in CDA patients makes differential diagnosis difficult; identification of the genetic variants is crucial in clinical management. We report the fifth case of a patient with unclassified CDAs, after genetic study, with CDA type IV.

Sideroblastic anemia: functional study of two novel missense mutations in ALAS2.

BACKGROUND: X-linked sideroblastic anemia (XLSA) is a disorder characterized by decreased heme synthesis and mitochondrial iron overload with ringed sideroblasts in bone marrow. XLSA is caused by mutations in the erythroid-specific gene coding 5-aminolevulinate synthase (ALAS2). Anemia in XLSA is extremely variable, characteristically microcytic and hypochromic with poikilocytosis, and the red blood cell distribution width is increased and prominent dimorphism of the red cell population. Anemia in XLSA patients responds variably to supplementation with pyridoxine. METHODS AND RESULTS: We report four patients with XLSA and three mutations in ALAS2: c.611G>A (p.Arg204Gln), c.1218G>T (p.Leu406Phe) and c.1499A>G (p.Tyr500Cys). The in silico predictions of three ALAS2 mutations and the functional consequences of two ALAS2 mutations were assessed. We performed in silico analysis of these mutations using ten different softwares, and all of them predicted that the p.Tyr500Cys mutation was deleterious. The in vitro prokaryotic expression showed that the p.Leu406Phe and p.Tyr500Cys mutations reduced the ALAS2 specific activity (SA) to 14% and 7% of the control value, respectively. CONCLUSION: In view of the results obtained in this study, a clear relationship between genotype and phenotype cannot be established; clinical variability or severity of anemia may be influenced by allelic variants in other genes or transcription factors and environmental conditions.

Microcytic anemia in a pregnant woman: beyond iron deficiency.

Sideroblastic anemias are a heterogeneous group of disorders characterized by anemia of varying severity and the presence of ringed sideroblasts in bone marrow. The most common form of inherited sideroblastic anemia is X-linked sideroblastic anemia (XLSA). In many XLSA patients, anemia responds variably to supplementation with pyridoxine (vitamin B6). We describe the case of a pregnant female with XLSA who had a novel mutation on the ALAS2 gene (c.1218G > T, p.Leu406Phe). Oral chelation therapy was contraindicated and high-dose vitamin B6 would have possible side effects in pregnancy. Serum hepcidin level was very low, indicating increased absorption of iron secondary to ineffective erythropoiesis. Therapy was begun with a low dose of pyridoxine that was increased post-partum. The patient's liver showed moderate iron deposits. During a subsequent 3-month period of pyridoxine supplementation, serum ferritin level and transferrin saturation decreased, hemoglobin content and serum hepcidin level normalized, and morphologic red cell abnormalities improved markedly. The patient responded well to treatment, showing the pyridoxine responsiveness of this novel ALAS2 mutation. The baby girl had the same mutation heterozygously, and although she was neither anemic nor showed abnormalities in a peripheral blood smear, she had a mild increment in RDW and her condition is now being followed.

Mutations in the HFE, TFR2, and SLC40A1 genes in patients with hemochromatosis.

Hereditary hemochromatosis causes iron overload and is associated with a variety of genetic and phenotypic conditions. Early diagnosis is important so that effective treatment can be administered and the risk of tissue damage avoided. Most patients are homozygous for the c.845G>A (p.C282Y) mutation in the HFE gene; however, rare forms of genetic iron overload must be diagnosed using a specific genetic analysis. We studied the genotype of 5 patients who had hyperferritinemia and an iron overload phenotype, but not classic mutations in the HFE gene. Two patients were undergoing phlebotomy and had no iron overload, 1 with metabolic syndrome and no phlebotomy had mild iron overload, and 2 patients had severe iron overload despite phlebotomy. The patients' first-degree relatives also underwent the analysis. We found 5 not previously published mutations: c.-408_-406delCAA in HFE, c.1118G>A (p.G373D), c.1473G>A (p.E491E) and c.2085G>C (p.S695S) in TFR2; and c.-428_-427GG>TT in SLC40A1. Moreover, we found 3 previously published mutations: c.221C>T (p.R71X) in HFE; c.1127C>A (p.A376D) in TFR2; and c.539T>C (p.I180T) in SLC40A1. Four patients were double heterozygous or compound heterozygous for the mutations mentioned above, and the patient with metabolic syndrome was heterozygous for a mutation in the TFR2 gene. Our findings show that hereditary hemochromatosis is clinically and genetically heterogeneous and that acquired factors may modify or determine the phenotype.

[Hyperferritinemia, ferropenia and metabolic syndrome in a patient with a new mutation of gene TFR2 and another in gene FTL. A family study]. / Hiperferritinemia, ferropenia y síndrome metabólico en un paciente con una nueva mutación en el gen TFR2 y otra en el gen FTL. Estudio familiar.

BACKGROUND AND OBJECTIVES: Hyperferritinemia is a common finding in clinical practice. This condition can be congenital or acquired, although it is not always associated with iron overload. Genetic hyperferritinemia is associated with iron overload, hereditary hemochromatosis, or cataracts that progress without iron overload (hereditary hyperferritinemia-cataract syndrome). Metabolic syndrome is associated with hyperferritinemia and mild iron overload, with no increase in transferrin saturation. We report a family with hyperferritinemia. PATIENTS AND METHODS: We present the study of a family with dual hyperferritinemia (congenital and acquired) and an analysis of the genes involved in iron metabolism. RESULTS: Patients with hereditary hyperferritinemia-cataract syndrome have the mutation c.-167C>T in the FTL gene; patients with metabolic syndrome present a new mutation in the TFR2 gene (c.1259G>A, p.Arg420His). CONCLUSIONS: The phenotypic and genotypic diversity of hyperferritinemia makes it a diagnostic challenge for clinicians. Basic research and clinical research should be combined to ensure better patient care.

Hiperferritinemia, ferropenia y síndrome metabólico en un paciente con una nueva mutación en el gen TFR2 y otra en el gen FTL. Estudio familiar / Hyperferritinemia, ferropenia and metabolic syndrome in a patient with a new mutation of gene TFR2 and another in gene FTL. A family study

Fundamento y objetivo: La hiperferritinemia es un hallazgo común en la práctica clínica diaria que puede ser congénita o adquirida y no siempre se asocia con sobrecarga férrica. La hiperferritinemia genética puede acompañarse de sobrecarga, como en la hemocromatosis hereditaria, o cursar con cataratas sin sobrecarga, en ese caso es el síndrome hereditario de hiperferritinemia y cataratas. Por otra parte, el síndrome metabólico puede cursar con hiperferritinemia y sobrecarga leve-moderada pero sin aumento de saturación de transferrina. Presentamos una familia con hiperferritinemia.Pacientes y método: Estudio de una familia con hiperferritinemia dual, congénita y adquirida, con análisis de los genes implicados en el metabolismo del hierro. Resultados:Los pacientes con síndrome hereditario de hiperferritinemia y cataratas tienen la mutación c.-167C>T en heterocigosis en el gen FTL. El paciente con síndrome metabólico presenta, además, una nueva mutación en heterocigosis en el gen TFR2 (c.1259G>A, p.Arg420His). Conclusiones: La hiperferritinemia, habitualmente casual, supone para el clínico un reto diagnóstico por sus diversidades fenotípicas y genotípicas, siendo necesario aunar esfuerzos en investigación básica y clínica para la asistencia de los pacientes (AU)

Background and objetives: Hyperferritinemia is a common finding in clinical practice. This condition can be congenital or acquired, although it is not always associated with iron overload. Genetic hyperferritinemia is associated with iron overload, hereditary hemochromatosis, or cataracts that progress without iron overload (hereditary hyperferritinemia-cataract syndrome). Metabolic syndrome is associated with hyperferritinemia and mild iron overload, with no increase in transferrin saturation. We report a family with hyperferritinemia. Patients and methods: We present the study of a family with dual hyperferritinemia (congenital and acquired) and an analysis of the genes involved in iron metabolism. Results: Patients with hereditary hyperferritinemia-cataract syndrome have the mutation c.-167C>T in the FTL gene; patients with metabolic syndrome present a new mutation in the TFR2 gene (c.1259G>A, p.Arg420His).Conclusions: The phenotypic and genotypic diversity of hyperferritinemia makes it a diagnostic challenge for clinicians. Basic research and clinical research should be combined to ensure better patient care (AU)