Codanin-1 mutations engineered in human erythroid cells demonstrate role of CDAN1 in terminal erythroid maturation.

The generation of a functional erythrocyte from a committed progenitor requires significant changes in gene expression during hemoglobin accumulation, rapid cell division, and nuclear condensation. Congenital dyserythropoietic anemia type I (CDA-I) is an autosomal recessive disease that presents with erythroid hyperplasia in the bone marrow. Erythroblasts in patients with CDA-I are frequently binucleate and have chromatin bridging and defective chromatin condensation. CDA-1 is most commonly caused by mutations in Codanin-1 (CDAN1). The function of CDAN1 is poorly understood but it is thought to regulate histone incorporation into nascent DNA during cellular replication. The study of CDA-1 has been limited by the lack of in vitro models that recapitulate key features of the disease, and most studies on CDAN1 function have been done in nonerythroid cells. To model CDA-I we generated HUDEP2 mutant lines with deletion or mutation of R1042 of CDAN1, mirroring mutations found in CDA-1 patients. CDAN1 mutant cell lines had decreased viability and increased intercellular bridges and binucleate cells. Further, they had alterations in histone acetylation associated with prematurely elevated erythroid gene expression, including gamma globin. Together, these data imply a specific functional role for CDAN1, specifically R1042 on exon 24, in the regulation of DNA replication and organization during erythroid maturation. Most importantly, generation of models with specific patient mutations, such as R1042, will provide further mechanistic insights into CDA-I pathology.

Hepatic and cardiac iron load as determined by MRI T2* in patients with congenital dyserythropoietic anemia type I.

Iron overload comprises one of the main complications of congenital dyserythropoietic anemia type I (CDA-I). When analyzing magnetic resonance imaging T2* (MRI T2*) results in CDA patients, two previous studies reported discordant results regarding iron load in these patients. To further understand iron loading pattern in this group of patients, we analyzed MRI T2* findings in 46 CDA-I patients. Mild to moderate hepatic iron overload was detected in 28/46 (60.8%) patients. A significant correlation was found between serum ferritin and liver iron concentration (LIC). A significant correlation (p value = 0.02) was also found between the patient's age and LIC, reflecting increased iron loading over time, even in the absence of transfusion therapy. Notably, no cardiac iron overload was detected in any patient. Transfusion-naive patients had better LIC and better cardiac T2* values. These results demonstrate that a high percentage of CDA-I patients have liver iron concentration above the normal values, risking them with significant morbidity and mortality, and emphasize the importance of periodic MRI T2* studies for direct assessment of tissue iron concentration in these patients, taking age and transfusional burden into consideration.

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.

Fetal presentation of congenital dyserythropoietic anemia type 1 with novel compound heterozygous CDAN1 mutations.

The congenital dyserythropoietic anemias are a heterogeneous group of disorders characterized by anemia and ineffective erythropoiesis. Congenital dyserythropoietic anemia type I (CDA1) can present in utero with hydrops fetalis, but more often it presents in childhood or adulthood with moderate macrocytic anemia, jaundice, and progressive iron-overload. CDA1 is inherited in an autosomal recessive manner, with biallelic pathogenic variants in CDAN1 or C15orf41. This case report documents a severe fetal presentation of CDA1 where we identified two novel compound heterozygous mutations in CDAN1 and describes the associated pathologic findings and levels of iron-regulatory proteins hepcidin, erythroferrone, and GDF15.

Heavy metal levels in patients with ineffective erythropoiesis.

OBJECTIVES: Iron is taken into enterocytes at the duodenum via apical divalent metal-ion transporter 1 protein. Besides iron, divalent metal-ion transporter 1 also transports other divalent metals. We aimed to investigate blood heavy metal levels in patients with ineffective erythropoiesis. METHODS: Blood levels of heavy metals including Pb, Al, Cd, Cr, Co, Cu, and Zn were measured in patients with thalassemia major (TM), thalassemia intermedia (TI), congenital dyserythropoietic anemia (CDA), and age- and sex-matched healthy controls. RESULTS: Blood samples were obtained from 68 patients (51 patients with TM, 8 with TI, 9 with CDA), and a control group that included 65 volunteers. Patients with TM were found to have lower Al, Pb, and Zn, and higher Cd levels compared with the control group. The patients treated with deferasirox were further analyzed and Pb and Zn levels were found lower compared with the control group. DISCUSSION: Patients with TM had tendency to have elevated levels of plasma cadmium; however, the median level was not at a toxic level. Increased metal-ion transporter 1 activity may cause heavy metal accumulation, but deferasirox chelation may be protective against heavy metals besides iron.

Morphological features of congenital dyserythropoietic anemia type I: The role of electron microscopy in diagnosis.

INTRODUCTION: Congenital dyserythropoietic anemias are rare blood disorders characterized by congenital anemia and a wide range of morphological and functional abnormalities of erythroid precursors. OBJECTIVES: To analyze the relative frequency of both light microscopic (LM) and electron microscopic (EM) morphological features of erythroblasts in a large group of patients with molecular proven congenital dyserythropoietic anemia type I (CDAI). METHODS: We retrospectively evaluated the LM and EM of bone marrow (BM) erythroblasts in 35 patients with CDAI. Thirty-four patients carried the CDAN1 Arg1042Trp founder mutation and one the p.Pro1130Leu mutation. BM slides of 24 patients were available for LM examination. EM studies were performed in all 35 patients. RESULTS: On LM, marked erythroid hyperplasia, binuclear erythroblasts, and various non-specific dyserythropoietic features were documented in every case; internuclear chromatin bridges were detected in 19 patients (79%). In all, EM of erythroblasts revealed a spongy appearance of heterochromatin, a widening of nuclear pores, and invagination of cytoplasm into the nuclear region. CONCLUSIONS: EM studies revealed high morphological frequency of specific ultrastructural changes in erythroblasts which facilitate prompt diagnosis of CDAI. Due to low specificity of BM LM findings, when BM EM is unavailable diagnostic approach should also include other inherited anemias.

Proton pump inhibitors use suppresses iron absorption in congenital dyserythropoietic anemia.

Congenital dyserythropoietic anemia type I (CDA I) is associated, as other anemic noninflammatory states, with ineffective erythropoiesis and increased iron absorption, which may lead to complication of iron overload. The latter complication requires iron-chelating therapy, which may be associated with adverse effects and toxicity. Gastric acid production is known to be an important factor that facilitates non-heme iron absorption. The purpose of this study was to examine whether treatment with proton pump inhibitors (PPIs) can decrease iron absorption in patients with CDA I. Eight CDA I patients (4 boys) aged 12-18 years with mild iron overload (not yet requiring chelating therapy) received 20 mg/d omeprazole for 6 months. Blood samples were obtained for ferritin, C-reactive protein, hemoglobin, calcium, and magnesium at baseline, at the end of months intervention and 6 months after its cessation. The mean ferritin level decreased from 585 ± 180 ng/ml at baseline to 522 ± 172 ng/ml at the end of 6-month treatment and 660 ± 256 ng/ml 6 months after cessation of omeprazole treatment (p  =  0.009). Omeprazole treatment caused a nonsignificant reduction in the mean iron level (iron 159 ± 42, 136 ± 54,167 ± 34 µg/dl, p  =  0.302). However, mean hemoglobin level was mildly but significantly reduced (Hg 10.0 ± 0.8, 9.55 ± 1.0, 10.4 ± 10.7 g/dl, p  =  0.002). No adverse effects were reported. Our investigation suggests that administration of PPI to patients with CDA I may reduce iron absorption and may lower iron overload and the need for chelation therapy.

Fibrin clot structure in patients with congenital dysfibrinogenaemia.

The clinical phenotype of patients with congenital dysfibrinogenaemia is highly heterogeneous, from absence of symptoms to mild bleeding, or thrombosis. A few mutations are associated with a specific phenotype, but generally the clinical course is not predictable. We investigated whether fibrin clot properties are correlated with the patient's phenotype and/or genotype. Ex vivo plasma fibrin clot characteristics, including turbidity, fibrinolysis, clot permeability and fibrin fibre density assessed by laser scanner confocal microscopy were investigated in 24 genotyped patients with congenital dysfibrinogenaemia compared to normal pool plasma. Compared to normal pool plasma, the patients were characterised by slower fibrin polymerisation (lag time, 345.10 ± 22.98 vs. 166.00s), thinner fibrin fibres (maximum absorbance, 0.15 ± 0.01 vs. 0.31), prolonged clot lysis time (23.72 ± 0.97 vs. 20.32 min) and larger clot pore size (21.5×10(-9) ± 4.48×10(-9) vs. 7.96×10(-9)cm(2)). Laser scanning confocal microscopy images confirmed disorganised fibrin networks in all patients. Patients with tendency to bleed showed an increased permeability compared to asymptomatic patients (p=0.01) and to patients with a thrombotic history (p=0.02) while patients with thrombotic history had a tendency to have a prolonged clot lysis time. Fibrin clot properties were similar among hotspot mutations. Further studies including a larger number of patients are needed to evaluate whether analysis of permeability and clot lysis time may help to distinguish the clinical phenotype in these patients and to assess differences according to the genotype.

The diagnostic challenge of congenital dyserythropoietic anaemia: two cases of 'CDA type II'.

The congenital dyserythropoietic anaemias (CDAs) are a group of rare hereditary disorders characterised by ineffective erythropoiesis and morphological abnormalities in the erythroblasts. Patients may present with jaundice or with symptoms of anaemia, gall stones or iron overload. The diagnosis can be challenging and cases have been confused with haemolytic anaemia, haemochromatosis or a haemoglobinopathy. A delayed diagnosis can lead to inappropriate treatment or delayed management of iron overload. We present two patients previously diagnosed as CDA type II in whom the diagnosis was revised to CDA type I and to hereditary spherocytosis. The conditions are compared and the approach to diagnosis is discussed.

High levels of soluble serum hemojuvelin in patients with congenital dyserythropoietic anemia type I.

OBJECTIVE: Congenital dyserythropoietic anemia (CDA) is a rare group of red blood cell disorders with ineffective erythropoiesis and secondary hemochromatosis. Inappropriate suppression of hepcidin and high levels of growth differentiation factor 15 (GDF15) have been described in CDA I and II patients, probably contributing to secondary hemochromatosis. Hemojuvelin (HJV) is an important regulator of serum hepcidin, while soluble form of HJV (s-HJV) competitively down-regulates hepcidin. METHODS: We determined the soluble hemojuvelin (s-HJV) levels in 17 patients with CDA I and in 17 healthy volunteers (HV) and looked for correlations with other parameters of iron overload and erythropoiesis. RESULTS: Significantly higher levels of s-HJV were found in patients (2.32 ± 1.40 mg/L) compared with healthy volunteers (0. 69 ± 0.44 mg/L) (P = 0.001). Western blot analysis confirmed the presence of high levels of s-HJV in CDA I patients. s-HJV positively correlated with serum ferritin, erythropoietin, soluble transferrin receptor, and GDF15 and negatively correlated with hepcidin to ferritin ratios. CONCLUSIONS: We for the first time documented high levels of serum s-HJV in CDA I patients, suggesting that it may contribute to iron loading pathology in CDA I and eventually in other anemias with ineffective erythropoiesis.

A case of congenital dyserythropoietic anemia type 1 in a Japanese adult with a CDAN1 gene mutation and an inappropriately low serum hepcidin-25 level.

We describe the first case of genetically diagnosed congenital dyserythropoietic anemia (CDA) type 1 in a Japanese man. The patient had hemolytic anemia since he was a child, and he developed diabetes, hypogonadism, and liver dysfunction in his thirties, presumably from systemic iron overload. When he was 48 years old a diagnosis was finally made by genetic analysis that revealed a homozygous mutation of CDAN1 gene (Pro1129Leu). His serum hepcidin-25 level was inappropriately low. We conclude that physicians should be aware of the possibility of CDA in a patient with anemia and systemic iron overload at any age.

Two founder mutations in the SEC23B gene account for the relatively high frequency of CDA II in the Italian population.

Congenital Dyserythropoietic Anemia type II is an autosomal recessive disorder characterized by unique abnormalities in the differentiation of cells of the erythroid lineage. The vast majority of CDA II cases result from mutations in the SEC23B gene. To date, 53 different causative mutations have been reported in 86 unrelated cases (from the CDA II European Registry), 47 of them Italian. We have now identified SEC23B mutations in 23 additional patients, 17 Italians and 6 non-Italian Europeans. The relative allelic frequency of the mutations was then reassessed in a total of 64 Italian and 45 non-Italian unrelated patients. Two mutations, E109K and R14W, account for over one-half of the cases of CDA II in Italy. Whereas the relative frequency of E109K is similar in Italy and in the rest of Europe (and is also prevalent in Moroccan Jews), the relative frequency of R14W is significantly higher in Italy (26.3% vs. 10.7%). By haplotype analysis we demonstrated that both are founder mutations in the Italian population. By using the DMLE+ program our estimate for the age of the E109K mutation in Italian population is ≈2,200 years; whereas for the R14W mutation it is ≈3,000 years. We hypothesize that E109K may have originated in the Middle East and may have spread in the heyday of the Roman Empire. Instead, R14W may have originated in Southern Italy. The relatively high frequency of the R14W mutation may account for the known increased prevalence of CDA II in Italy.