Congenital dyserythropoietic anemias

From bench to bedside: The promise of sotatercept in hematologic disorders

Sotatercept (ACE-011) is an activin receptor IIA-Fc (ActRIIA-Fc) fusion protein currently under investigation for its potential in the treatment of hematologic diseases. By impeding the activities of the overexpressed growth and differentiation factor 11 (GDF11), activin A, and other members of the transforming growth factor-β (TGF-β) superfamily, commonly found in hematologic disorders, sotatercept aims to restore the normal functioning of red blood cell maturation and osteoblast differentiation. This action is anticipated to enhance anemia management and hinder the progression of myeloma. Simultaneously, comprehensive research is ongoing to investigate sotatercept's pharmacokinetics and potential adverse reactions, thus laying a robust foundation for its prospective clinical use. In this review, we provide a detailed overview of TGF-β pathways in physiological and hematologic disorder contexts, outline the potential mechanism of sotatercept, and delve into its pharmacokinetics and clinical research advancements in various hematologic diseases. A particular emphasis is given to the relationship between sotatercept dosage and its efficacy or associated adverse reactions.

Congenital dyserythropoietic anaemia type II: a rare entity

Congenital dyserythropoietic anaemias (CDAs) are a group of rare hereditary disorder characterised by ineffective erythropoiesis and dyserythropoiesis. Among the three variants, type II is the most common. The authors are presenting two cases of CDA type II in two sisters.

Molecular analysis of 42 patients with congenital dyserythropoietic anemia type II: new mutations in the SEC23B gene and a search for a genotype-phenotype relationship

BACKGROUND

The most frequent form of congenital dyserythropoietic anemia is the type II form. Recently it was shown that the vast majority of patients with congenital dyserythropoietic anemia type II carry mutations in the SEC23B gene. Here we established the molecular basis of 42 cases of congenital dyserythropoietic anemia type II and attempted to define a genotype-phenotype relationship.

DESIGN AND METHODS

SEC23B gene sequencing analysis was performed to assess the diversity and incidence of each mutation in 42 patients with congenital dyserythropoietic anemia type II (25 described exclusively in this work), from the Italian and the French Registries, and the relationship of these mutations with the clinical presentation. To this purpose, we divided the patients into two groups: (i) patients with two missense mutations and (ii) patients with one nonsense and one missense mutation.

RESULTS

We found 22 mutations of uneven frequency, including seven novel mutations. Compound heterozygosity for a missense and a nonsense mutation tended to produce a more severe clinical presentation, a lower reticulocyte count, a higher serum ferritin level, and, in some cases, more pronounced transfusion needs, than homozygosity or compound heterozygosity for two missense mutations. Homozygosity or compound heterozygosity for two nonsense mutations was never found.

CONCLUSIONS

This study allowed us to determine the most frequent mutations in patients with congenital dyserythropoietic anemia type II. Correlations between the mutations and various biological parameters suggested that the association of one missense mutation and one nonsense mutation was significantly more deleterious that the association of two missense mutations. However, there was an overlap between the two categories.

The congenital dyserythropoietic anemias

The congenital dyserythropoietic anemias (CDAs) are a heterogeneous group of hereditary disorders that seem to be restricted to the erythroid lineage. They are characterized by morphologic abnormalities of erythroid precursors in the bone marrow, resulting in ineffective erythropoiesis and a suboptimal reticulocyte response. As with many rare disorders, cases of CDA are often misdiagnosed, which may lead to inappropriate management. In this review, the authors highlight the relevant clinical data together with recent molecular advances that should aid decision making in diagnosis and patient management.

A splice site mutation confirms the role of LPIN2 in Majeed syndrome

Majeed syndrome is an autoinflammatory disorder consisting of chronic recurrent multifocal osteomyelitis, congenital dyserythropoietic anemia, and neutrophilic dermatosis. To date, 2 unrelated families with Majeed syndrome have been reported. Mutations in LPIN2 have been found in both families. Here we report a third consanguineous family with Majeed syndrome with a novel mutation. The patient, a 3-year-old Arabic girl, had hepatosplenomegaly and anemia as a neonate. At age 15 months, she developed recurrent episodes of fever and multifocal osteomyelitis. In addition, bone marrow aspiration demonstrated significant dyserythropoiesis, suggesting Majeed syndrome. Coding sequences and splice sites of LPIN2 were sequenced in the patient and her mother. A homozygous single-basepair change was detected in the donor splice site of exon 17 (c.2327+1G>C) in the patient; her mother was heterozygous at this site. These data confirm the role of LPIN2 mutations in the etiology of Majeed syndrome.

Quantification of nucleated red blood cells in allogeneic marrow graft and impact of processing on recovery

BACKGROUND

In allogeneic bone marrow transplantation (BMT), a higher nucleated and CD34+ cell dose has been reported to improve various outcomes. Other cell types, such as lymphocyte subsets, also influenced BMT results. While nucleated red blood cells (NRBCs) represent a subset of bone marrow (BM) cell subpopulation, the question of their quantification in BM grafts and the impact of BM processing on their recovery has not been addressed.

STUDY DESIGN AND METHODS

In a prospective study on 77 BM products, NRBCs were enumerated by flow cytometry and the recovery analyzed after manipulation. Because NRBCs could compromise white blood cell count, the impact of NRBC count on CD34+ cell percentage and total nucleated cell (TNC) dose were also determined.

RESULTS

The mean percentage of NRBCs in BM grafts was 21.6 percent (range, 7.8%-40.9%). Mean NRBC recoveries after BM concentration or RBC depletion were 98.4 and 28.7 percent, respectively, close to those obtained for TNC cells (88.6 and 31.3%, respectively). When corrected with NRBC count, the mean percentages of corrected CD34+ cell and TNC dose were significantly modified when compared with uncorrected values, whatever the type of BM manipulation.

CONCLUSION

Our data show that NRBC quantification might be of importance to improve quality control of BM products and to evaluate the influence of NRBCs cell dose on outcomes after BMT.

Advances in the understanding of the congenital dyserythropoietic anaemias

The congenital dyserythropoietic anaemias (CDAs) are a heterogeneous group of diseases in which the anaemia is predominantly caused by dyserythropoiesis and marked ineffective erythropoiesis; three major (types I, II and III) and several minor subgroups have been identified. Additional information on the natural history of these conditions, the beneficial role of splenectomy in CDA type II and efficacy of interferon-alpha in type I have recently been reported. A disease gene has been localised to a chromosomal segment in the three major types and in CDA type I, a disease gene has been identified (CDANI). Mutations have been detected in both familial and sporadic cases but the predicted protein structure gives few clues as to its function. In both type I and II, there are cases unlinked to the identified localisations, suggesting genetic heterogeneity.

Clinical and laboratory manifestations of congenital dyserythropoietic anemia type I in a cohort of French children

Congenital dyserythropoietic anemia type I (CDA I) is a rare disorder of erythropoiesis. The objective of this study was to describe the clinical and laboratory manifestations, the diagnosis procedure, the therapeutic approaches and outcome in CDA I. The 12 patients included belong to the retrospective French Multicenter Study. Clinical and biologic data were compiled. Biologic tests included light and, in some cases, electron microscopy, ektacytometry, and red cell membrane protein electrophoresis. Neonatal manifestations (anemia, early jaundice, and/or splenomegaly) and bone abnormalities were present in 11 of the 12 and 6 of the 12 patients, respectively. CDA I was initially misdiagnosed in four children. By the time of diagnosis, anemia with reticulocytosis lower than expected in a hemolytic anemia was present in all patients. Bone marrow electron microscopy examination revealed characteristic findings in all nine children. Red cell membrane protein 4.1 was reduced in all five children. At least one transfusion was required in 11 of the 12 children. Interferon alpha2 corrected anemia in the three children who received monthly transfusions. CDA I is commonly misdiagnosed in children. It should be sought in patients with unexplained chronic anemia, especially when associated with neonatal manifestations, jaundice, splenomegaly, subnormal or low reticulocytosis, and congenital bone malformations.

Ineffective erythropoiesis underlies the clinical heterogeneity of congenital dyserythropoietic anemia type II (CDA II)

BACKGROUND

Congenital dyserythropoietic anemia type II (CDA II) is an autosomal recessive disease, and is the most common CDA. The qualitative and quantitative defects of erythropoiesis in CDA II, as estimated by the hematological and biochemical parameters at the time of diagnosis, may not reflect the heterogeneity of the disease course of each patient.

METHODS

Three pediatric patients with CDA II are herein presented, having an heterogeneous clinical course. In addition to bone marrow morphology, Ham test and SDS-PAGE of erythrocyte membrane protein, the present study also examined erythroid marrow activity, by measuring serum Erythropoietin (Epo), soluble Transferrin Receptors (sTfR) concentrations and Reticulocyte Production Index (RPI).

RESULTS

All patients demonstrated the same pattern of ineffective erythropoiesis, having increased Epo (350-389 IU/L), sTfR concentrations (6.2-7.8 mg/L) and low RPI values (0.8-1.3). Erythron expansion was expressed by RPI values nearly twofold higher than normal values in parallel to raised sTfR and high Epo production. Despite the same degree of ineffective erythropoiesis seen in all patients, the severity of the clinical course was diverse in terms of frequency and clinical relevance of transfusion needs.

CONCLUSION

An analysis of the parameters expressing ineffective erythropoiesis in CDA II can provide a better understanding of the degree of dyserythropoiesis, however it is not useful for predicting the clinical course of disease in patients, because the underlying genetic heterogeneity of this disorder remains obscure.

Acute parvovirus B19 infection mimicking congenital dyserythropoietic anemia

Infection with human parvovirus B19 is known to cause transient erythroid aplasia in children with hemolytic anemia but has also been associated with bone marrow necrosis and morphologic changes suggesting myelodysplasia. The authors describe a previously healthy child who presented with severe hypoplastic anemia. Initial bone marrow aspiration revealed erythroid hyperplasia, dyserythropoiesis, and multinucleated erythroid cells with nuclear budding and bridging, consistent with the diagnosis of congenital dyserythropoietic anemia. Serologic testing documented acute parvovirus infection, and on recovery the correct diagnosis of unsuspected congenital spherocytosis was established. This case expands the spectrum of hematologic disease associated with acute parvovirus infection.

The Drosophila Cell Survival Gene discs lost Encodes a Cytoplasmic Codanin-1-like Protein, Not a Homolog of Tight Junction PDZ Protein Patj

The Drosophila gene discs lost (dlt) has been reported to encode a homolog of the vertebrate tight junction PDZ protein Patj, and was thought to play a role in cell polarity. Using rescue experiments and sequence analyses, we show that dlt mutations disrupt the Drosophila Codanin-1 homolog, a cytoplasmic protein, and not the PDZ protein. Mutations in human Codanin-1 are associated with congenital dyserythropoietic anemia type I (CDA I). In Drosophila, the genomic organization of dlt is unusual. dlt shares its first untranslated exon with alpha-spectrin, and both genes are coexpressed throughout development. We show that dlt is not required for cell polarity but is needed for cell survival and cell cycle progression. Finally, we present evidence that the PDZ protein previously thought to be encoded by dlt is not required for viability. We propose to rename this PDZ protein after its vertebrate homolog, Patj (Pals-associated tight junction protein).

Congenital dyserythropoietic anaemia type II (HEMPAS) and haemochromatosis: a report of two cases

We describe two patients with severe iron overload in the context of congenital dyserythropoietic anaemia (CDA) type II, which is characterized by a protein glycosylation defect with impairment of N-glycan synthesis. In both patients a corpuscular, haemolytic anaemia had been diagnosed in early childhood and both patients underwent splenectomy before the age of 9 years. They developed clinical manifestations of haemochromatosis and only re-evaluation during adulthood led to the correct diagnosis. Abnormal glycosylation of proteins involved in iron homeostasis is likely to contribute to the massive hepatic iron accumulation characteristic for CDA type II. Both patients required chelation therapy. This report points out the need to consider CDA in patients presenting with haemochromatosis and anaemia.

Ultrastructural characterization of the erythroid cells in a novel case of congenital anemia

Congenital dyserythropoietic anemia type I (CDA-I) is a rare genetic disease that affects erythropoiesis. On the other hand, hemoglobin H (HbH) disease is a severe form of alpha-thalassemia. We herein present ultrastructural and immunocytochemical data concerning the first reported case of congenital anemia with clinical and molecular diagnosis of HbH disease complicated by CDA-I-specific dysplasies of the erythroid cells. Fine structure and transmission electron microscope immunolabeling analysis of the bone marrow and peripheral blood samples were consistent with a potential co-existence of the two defects in the same patient, producing a novel and diagnostically important dyserythropoietic profile. In the patient under investigation both nuclear and plasma membrane of the erythroid cells are almost equally defective. The unknown defect causes the concomitant precipitation of beta- and alpha-globin chains (or hemoglobin), along with an unidentified protein(s). The unusual inclusions gain access to the euchromatin area and exhibit higher affinity for the plasma membrane than the classic inclusions of precipitated alpha- or beta-globin chains seen in thalassemia. The affected erythroid precursors are presented with severe nuclear distortions, endonuclear globin loads, morphological evidence of apoptosis and increased erythrophagocytosis. Plasma membrane distortions and the rate of protein precipitation were aggravated with differentiation. Our findings provide additional evidence for a specific activation of a beta-thalassemic-like mechanism in CDA-I, containing not only the hemoglobin biosynthesis as previously suggested, and interpret the prototypal hematological portrait, which is an HbH disease, modified and partially counterbalanced by the effect of CDA-I or an unidentified CDA-I-like disease. The reported data describe the complexity of the interactions between the CDA-I and the HbH disease, revealing essential pathogenic events of the novel anemia and, indirectly, of the CDA-I.

Blackfan-Diamond anemia and dyserythropoietic anemia presenting with increased nuchal translucency at 12 weeks of gestation

Blackfan-Diamond anemia is a congenital hypoplastic anemia with a birth prevalence of about 1 in 200,000, usually presenting in the first few months of life and commonly associated with cardiac, urogenital and digital anomalies. Congenital dyserythropoietic anemias are a group of rare congenital anemias characterized by ineffective erythropoiesis. We report on two cases of congenital fetal anemia, one with Blackfan-Diamond anemia and one with dyserythropoietic anemia, presenting with increased nuchal translucency at 12 weeks of gestation.

Transfusion-dependent congenital dyserythropoietic anemia type I successfully treated with allogeneic stem cell transplantation

Until recently, therapy for patients with severe congenital dyserythropoietic anemia (CDA) has been limited to blood transfusions and chelation therapy. Three children with transfusion-dependent CDA type I underwent allogeneic stem cell transplantation (SCT) from matched sibling donors. Conditioning was with cyclophosphamide 50 mg/kg/day for 4 days, busulphan 4 mg/kg/day for 4 days, and antithymocyte globulin (ATG) 30 mg/kg for four doses pre-SCT. All patients engrafted and are alive, and transfusion independent. To our knowledge, this is the first report of successful SCT in the management of CDA type I.

A novel case of haemoglobin H disease associated with clinical and morphological characteristics of congenital dyserythropoietic anaemia type I

We report, for the first time, an unusual case of congenital anaemia with the clinical diagnosis of haemoglobin H disease complicated by morphological features at the light and electron microscopy level very similar to those of CDA-I. The red cell indices and the globin chain biosynthetic ratio were not characteristic of the defective haemoglobin genotype. The haematological, clinical and morphological data strongly suggest the novel coexistence of the two defects in a patient. The disease is characterised by a unique dyserythropoietic phenotype of diagnostic importance, which possibly brings new data regarding the reciprocal interaction between the two diseases, especially concerning a specific abnormality in globin chain synthesis in CDA-I, as previously suggested.

Congenital dyserythropoietic anaemia type II: a case study

A 13-year-old girl with chronic anaemia showed features of congenital dyserythropoietic anaemia (CDA) type II. The main clinical and haematological findings were splenomegaly, a mild microcytic anaemia, and numerous bizarre and binucleate normoblasts in the bone marrow. The acidified serum lysis test (Ham's test) performed with 5 normal sera was positive. The patient's red blood cells showed a markedly increased expression of the i red blood cell antigen.

Clinical and laboratory manifestations of congenital dyserythropoietic anemia type I in young adults

OBJECTIVES

Congenital dyserythropoietic anemia (CDA) type I is a rare autosomal recessive macrocytic anemia whose natural history is not well documented. The aim of the present study was to evaluate the clinical picture of the disease in young adults.

METHODS

The study sample consisted of 17 patients of mean age 11.9 +/- 5.4 yr (range 18-33 yr) and one older patient (age 44 yr), all Israeli Bedouins. The degree of anemia was evaluated as well as the extent of development of gallstones and iron overload. In each subject we determined the hemochromatosis gene mutations and the uridine dyphosphate-glucoronosyltransferase (UGT-1A) gene polymorphism associated with Gilbert's syndrome.

RESULTS

The patients were found to have moderate anemia, with the women displaying lower mean hemoglobin levels than the men (8.2 +/- 0.9 g dL(-1) vs. 10 +/- 1.3 g dL(-1); P=0.0059). The majority of patients (59%) had received at least one blood transfusion, with the women having a significantly higher transfusion requirement. Although delayed puberty was noted, final height and weight were within normal limits, and eight patients had progeny. Biliary stones were found in three of 16 patients, two of whom were homozygous for UGT-1A gene polymorphism. None of the patients carried the common hemochromatosis gene mutation, although serum ferritin levels were moderately elevated (788 +/- 332 ng mL(-1)).

CONCLUSIONS

CDA type I in young adults is characterized by moderate macrocytic anemia, more severe in women, and a tendency to cholelithiasis and secondary progressive iron overload. We suggest that iron overload in this patient population should be monitored and chelation therapy initiated when indicated to prevent organ damage

Glycoconjugate abnormalities in patients with congenital dyserythropoietic anaemia type I, II and III

Congenital dyserythropoietic anaemia type II (CDA II) is well known for glycosylation abnormalities affecting erythrocyte membrane glycoconjugates that encompass hypoglycosylation of band 3 glycoprotein and accumulation of glycosphingolipids: lactotriaosylceramides, neolactotriaosylceramide and polyglycosylceramides. These abnormalities were not observed in erythrocytes from patients with CDA of either type I or III. Recently, however, we have described a CDA type I patient in Poland with identical, though less pronounced, glycoconjugate abnormalities to those observed in patients with CDA type II. The abnormalities included partial unglycosylation of O-linked glycosylation sites in glycophorin A. These abnormalities are now reported in three Bedouin patients from Israel with CDA type I. In addition, the erythrocyte membranes of these patients exhibited highly increased globotetraosylceramide content. Glycoconjugate abnormalities were also present in erythrocyte membranes from three patients from Northern Sweden with CDA type III but they almost exclusively affected glycosphingolipids. In erythrocytes of all patients examined including one with CDA type II, polyglycosylceramides were significantly hypoglycosylated although, on a molar basis, their contents in erythrocyte membranes were increased. Thus, glycoconjugate abnormalities of varying intensity occur in erythrocyte membranes from all patients with CDA that were investigated.