先天性赤血球形成異常性貧血

Congenital dyserythropoietic anemias (CDAs) include a heterogeneous group of conditions characterized by insufficient erythropoiesis giving rise to monolinear cytopenia. Based on the morphological features of erythroblasts, three major subtypes have been established: CDA Type I, CDA Type II, and CDA Type III. CDA Type II is the most common type of CDAs, and this disease is characterized by a normocytic anemia with a normal or slightly increased reticulocyte count. The bone marrow is hypercellular with erythroid hyperplasia and binucleated erythroblasts with two nuclei at the same maturation stage. The inheritance is autosomal recessive, and the disease is caused by biallelic mutations in the SEC28B gene. More than 100 pathogenetic variants have been identified. Here, we report on three patients from Somalia with CDA Type II caused by a new SEC23B sequence variant. They came to attention and were diagnosed in early adulthood. Cases 1 and 2 had mild anemia with signs of hemolysis, and Case 3 had mild anemia with reticulocytosis. The eosin-5-maleimide binding test showed reduced binding in all three patients. Molecular genetics disclosed homozygosity for the sequence variant NM_006363.6:c.1580T > C p.(Leu527Ser) in the SEC23B gene. A bone marrow aspirate was performed from Case 2, and the smear disclosed morphological abnormalities typical for CDA Type II.

Congenital Dyserythropoietic Anemia type I (CDA-I) is an autosomal recessive disease characterized by anemia due to ineffective erythropoiesis and results primarily from mutations in CDAN1, which encodes CODANIN1. Research efforts to understand the CDA-I pathogenesis have been impeded by the embryonic lethality of germline Cdan1 deleted mice as well as mice deleted for Cdan1 in the erythroid compartment, using the constitutively active EpoR-Cre allele. To study the function of CODANIN1 in adult erythropoiesis, we generated mice with inducible erythroid-specific biallelic Cdan1 deletion using the Gata1-CreERT2 allele. Following tamoxifen administration to adult mice, Cdan1 is excised, resulting in features of CDA-I, including anemia, impaired erythroid differentiation, disturbances in erythroblast cell cycle progression, and the finding of 'spongy' heterochromatin in bone marrow erythroblasts. These findings confirm a critical role for CODANIN1 in effective adult erythropoiesis and demonstrate the successful generation of an inducible CDA-I mouse model, which serves as a valuable platform for testing novel therapies for this orphan disease.

Congenital dyserythropoietic anemia is a group of hereditary disorders characterized by erythroid hyperplasia and ineffective erythropoiesis, resulting in anemia of varying severity. Congenital dyserythropoietic anemia Type 1 (CDA-1) is classically associated with biallelic mutations in the CDAN1 gene. Here, we report the first case of compound heterozygous CDAN1 mutations p.(D1043V) and p.(S1036F) in clinical practice, presenting in a 24-year-old woman with mild, asymptomatic macrocytic anemia and hyperferritinemia. These variants are currently classified as variants of uncertain significance; however, this report represents the first clinical case of this compound heterozygous CDAN1 variant combination in a patient with a phenotype consistent with CDA-1. As the phenotypic boundaries of CDA-1 continue to expand, clinicians should consider CDA-1 in the differential diagnosis of unexplained macrocytic anemia, even in the absence of severe anemia.

Congenital dyserythropoietic anemia type IV (CDA IV) is a rare inherited erythroid disorder within the broad phenotypic spectrum associated with pathogenic variants in Krüppel-like factor 1 (KLF1), a master transcriptional regulator of erythropoiesis. This study aimed to describe the clinical picture, genetic causes, global distribution, and treatment of CDA IV. We retrospectively reviewed three pediatric patients diagnosed and treated at the Department of Pediatrics, The First Affiliated Hospital of Guangxi Medical University, since December 2014. Demographic, clinical, genetic, laboratory, treatment, transplantation, and follow-up data were collected, including conditioning regimens, graft-versus-host disease (GVHD) prophylaxis, engraftment, complications, and donor chimerism. We also conducted a literature review of CDA IV cases reported worldwide between January 1991 and December 2024. All three children developed symptoms within the first month of life. They had neonatal jaundice and anemia. One of them needed intrauterine transfusion. Gene testing found four KLF1 variants: c.525_526insCGGCGCC, c.1012C > T, c.1012C > A, and c.973G > A. Before hematopoietic stem cell transplantation (HSCT), all three patients needed regular red blood cell transfusions and had iron overload. All three then received HSCT from a parent or sibling. Neutrophils and platelets engrafted in every case. Donor chimerism stayed above 95% during follow-up, and no graft failure happened. No patient had acute or chronic GVHD. Viral reactivation after HSCT was mainly cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infection, and no severe infection was seen. At the last follow-up, all three patients were free of transfusion. Serum ferritin levels went down after HSCT, but liver or heart iron overload did not fully go away in some patients. For carefully chosen children with severe transfusion-dependent KLF1-related red cell disease, allogeneic HSCT may be a feasible curative option. Stable donor chimerism and lasting freedom from transfusion can be achieved. CDA IV has many clinical forms and can be mistaken for thalassemia or Evans syndrome, so early gene testing is very important for correct diagnosis. In areas where thalassemia is common, KLF1 mutation screening should be considered when the cause of microcytic anemia is unclear. Bigger studies with longer follow-up are still needed to better judge the long-term results of HSCT.

Congenital dyserythropoietic anemia type II (CDA II) is a rare hyporegenerative inherited anemia, resulting from a mutation in SEC23B. In the present case, our patient exhibited moderate anemia, jaundice, hepatosplenomegaly, tea-colored urine, hyperbilirubinemia, and iron overload. Whole exome sequencing revealed that the patient carried a compound heterozygous genotype in SEC23B consisting of a previously unreported missense variant c.181T > C (p.C61R) and a known pathogenic variant c.1832G > A (p.R611Q). Bone marrow aspirate demonstrated erythroid hyperplasia with abnormal erythroblast morphology. Bioinformatic analysis predicted the protein structures, indicating that p.C61R and p.R611Q mutations induce structural changes in their surrounding regions. SEC23B mRNA and protein levels in peripheral blood mononuclear cells (PBMCs) were significantly reduced compared with those in normal control cells, supporting their pathogenicity. Accordingly, a diagnosis of CDA II was considered. In this study, we identified a compound heterozygous SEC23B genotype in the patient and demonstrated that missense mutations of p.C61R and p.R611Q resulted in reduced levels of SEC23B mRNA and protein, suggesting the association of this genotype with CDA II.