X-linked sideroblastic anemia (XLSA), caused by pathogenic variants in ALAS2, typically presents as microcytic anemia in males. However, heterozygous females occasionally exhibit an atypical macrocytic phenotype, often leading to diagnostic ambiguity and confusion with nutritional anemias or myelodysplastic syndromes. This study aims to characterize a novel ALAS2 variant and explore the possible mechanisms underlying macrocytosis in a female patient. We analyzed a 15-year-old female with an 8-year history of refractory macrocytic anemia. Diagnostic evaluations included hematological profiling, iron metabolism studies, and bone marrow examination. Whole-exome sequencing (WES) was employed to identify genetic variants, followed by Sanger validation. Protein structural modeling was performed using AlphaFold 3. The patient presented with severe macrocytic anemia, iron overload, and borderline folate status despite supplementation. WES identified a novel frameshift variant in ALAS2, c.1277dupT (p.M426Ifs*66), which supported the diagnosis of atypical XLSA. Structural modeling suggested that this variant alters the C-terminal region and may affect the conformation of the catalytic site, including the spatial configuration around Lys391, potentially impairing enzymatic function. Additional variants in DHX34, FANCI, and BRIP1 were also identified, although their potential contributions to the phenotype remain uncertain because functional evidence is lacking. In conclusion, we identified a novel, predicted loss-of-function variant in ALAS2 associated with early-onset macrocytic XLSA. Macrocytosis in this case may reflect a proposed "high-turnover" failure involving intramedullary attrition of mutant clones and stress-induced premature maturation of wild-type clones; however, this mechanism remains speculative. Secondary nutrient depletion and additional genetic variants may also contribute, although their roles require further validation. This case underscores the value of genomic sequencing in resolving atypical, refractory anemias in female patients and preventing long-term misdiagnosis.

Vitamin B6 depletion during carbidopa/levodopa therapy has been linked to polyneuropathy, seizures, and anemia, but the direct evidence is heterogeneous, and causality remains uncertain. We conducted a focused scoping review of direct empirical evidence on vitamin B6 biology during carbidopa/levodopa exposure and on vitamin B6-related clinical consequences supported by biochemical assessment. We also included studies of biomarker-guided monitoring, supplementation, and direct carbidopa-vitamin B6 chemistry. PubMed, Scopus, and Web of Science were searched without date or language limits on July 21, 2026. Of 656 database records, 448 unique records were screened, 161 reports were assessed in full, and 36 reports met the focused criteria. These comprised 34 reports involving human participants, including 18 group-level studies and 16 case reports or series, and two nonclinical experimental reports. Direct chemistry supports stable carbidopa-pyridoxal 5'-phosphate binding, and high-dose carbidopa exposure in dogs produced a preventable deficiency phenotype. Human studies reported lower vitamin B6 biomarkers most consistently with high or rapidly increased exposure, but findings were not uniform, and dose, route, advanced disease, nutrition, supplementation, and overlapping cohorts could not be separated. Severe deficiency accompanied axonal neuropathy, refractory seizures, and microcytic or sideroblastic-pattern anemia in individual case reports. No study established population-level incidence of vitamin B6 depletion or attributable clinical outcomes, a causal exposure threshold, an optimal testing interval, or a prophylactic dose. Direct vitamin B6 testing, interpreted with laboratory-specific reference intervals and complementary nutritional, hematologic, and neurologic assessment, is better supported by the available evidence than reliance on homocysteine alone. Prospective exposure-resolved studies are required before route-specific risk or universal supplementation can be recommended.

Sideroblastic Anemia with B-cell Immunodeficiency, Periodic Fever and Developmental Delay (SIFD) is a rare autosomal recessive disorder caused by biallelic pathogenic variants in the TRNT1 gene, encoding tRNA nucleotidyltransferase 1, an enzyme essential for mitochondrial and cytosolic protein translation. The disease is characterized by a wide phenotypic spectrum, ranging from isolated hematological involvement to multisystem inflammatory disease. Herein, we report a pediatric patient with early-onset sideroblastic anemia, recurrent inflammatory episodes, B-cell immunodeficiency, immune dysregulation (cytopenia refractory to conventional treatment, splenomegaly and chronic interstitial lung disease), ectodermal dysplasia, mild developmental delay with white-matter hypomyelination, and progressive multisystem involvement. Genetic testing identified two biallelic TRNT1 variants, the novel c.841G>C variant and the previously reported pathogenic c.1252dupA variant, inherited from the father and mother, respectively, confirming the diagnosis of SIFD. The patient required immunoglobulin replacement therapy and immunomodulatory treatment, including rituximab, with partial control of infectious and immune dysregulation manifestations. This case expands the clinical, immunological, and genetic spectrum of TRNT1-related disease and highlights that immune dysregulation may dominate the clinical course. SIFD should be considered in children presenting with sideroblastic anemia associated with recurrent unexplained inflammation, B-cell immunodeficiency, cytopenias, and multisystem involvement. Early genetic diagnosis is essential to guide monitoring, therapeutic decisions, and prognostic stratification.

Heme synthesis is critical for several biological processes, including mitochondrial energy production and oxygen delivery via hemoglobin. The initial and rate-limiting step in heme synthesis is the conjugation of glycine with succinyl-CoA to form 5-aminolevulinic acid (ALA), which is catalyzed by two closely related enzymes that are coded by highly homologous genes, known as ALAS1 and ALAS2. Loss-of-function variants in ALAS2 result in sideroblastic anemia, whereas gain-of-function variants result in porphyria. We present a case of a woman who died with severe metabolic acidosis and was found to have a rare variant in ALAS2. We propose the hypothesis that the ALAS2 variant, in conjunction with other factors, was responsible for her demise.

This article details the diagnosis and treatment of an elderly male patient with VEXAS syndrome who came with fatigue and fever.The patient thereafter developed several clinical manifestations，including macrocytic anemia，tracheal and bronchial wall thickening，polyarthritis，rashes，and elevated levels of inflammatory markers.The final clue for subsequent genetic testing came from the bone marrow smear，which showed vacuolar degeneration in the cytoplasm of immature granulocytes.The UBA1 gene testing showed the mutation c.121A>C （p.Met41Val），which confirmed the diagnosis of VEXAS syndrome.Following glucocorticoid therapy，the patient's clinical conditions were significantly ameliorated.However，the patient's recurrence of fever and anemia months after discontinuing glucocorticoid medication was consistent with the repeated relapses described in VEXAS syndrome.The whole diagnostic process for the patient suggests that in clinical settings，thorough integration of clinical clues is crucial for making an appropriate diagnosis.To accomplish precision therapy，clinicians must retain an open mind and actively participate in multidisciplinary collaboration.

Background and Clinical Significance: Sideroblastic anemia with immunodeficiency, fevers, and developmental delay (SIFD) syndrome is a rare autosomal recessive disorder caused by biallelic variants in the TRNT1 gene, which encodes tRNA nucleotidyltransferase 1. The disease typically presents early in life with microcytic anemia, recurrent febrile episodes, developmental delay, and immune dysfunction. Because of its rarity and variable clinical expression, diagnosis may be challenging, and broad genetic testing can identify additional variants whose clinical significance requires careful interpretation. Case Presentation: We report a 4-month-old male infant with recurrent febrile episodes, severe recurrent microcytic anemia, recurrent infections, mild psychomotor developmental delay, and multisystem involvement. Genetic analysis identified two heterozygous TRNT1 variants inherited from different parents and confirmed to be in trans: a maternally inherited pathogenic frameshift variant, c.428_431del, p.(Asp143Glyfs12), and a paternally inherited missense variant, c.1246A>G, p.(Lys416Glu), initially classified as a variant of uncertain significance and subsequently interpreted as likely pathogenic in the context of the clinical phenotype and segregation findings. These findings supported the diagnosis of TRNT1-related SIFD syndrome. An additional heterozygous pathogenic C7 variant, c.633_643del, p.(Ser212Hisfs4), was identified. No second pathogenic C7 allele was detected, and functional complement testing was not performed; therefore, complement component 7 deficiency could not be established. Conclusions: This case highlights the importance of early genetic evaluation in infants with recurrent fever, microcytic anemia, immune abnormalities, and multisystem involvement. It also emphasizes the need for cautious interpretation of additional monoallelic pathogenic variants detected by broad genetic panels when functional confirmation and a compatible inheritance pattern are lacking.

Sideroblastic anemia is a rare disease and one of the heterogeneous bone marrow disorders. Gene therapy is considered as a method for treating these patients. The CRISPR/Cas9 system can recognize specific genomic DNA sequences and create Double-Strand Breaks (DSBs) in DNA. In this study, we attempted to investigate the effect of different sgRNAs in creating targeted cleavage in the desired region using the CRISPR/Cas9 system and inducing changes in the disease-related gene. Following the design of six sgRNAs, recombinant pX458 and pX459 plasmids harboring the respective sgRNA sequences were constructed and transfected into HEK293T cells. After transfection, the efficiency of targeted cleavage of the designed sgRNAs was evaluated using polyacrylamide gel electrophoresis (PAGE)-based analysis of the target amplicons and subsequently confirmed by Sanger sequencing. Based on the sequencing results, it was shown that in three out of four samples examined, the CRISPR/Cas9 system successfully created targeted disruption at the desired site. Here, we report that the choice of sgRNA target site affects its targeted cleavage activity and show that the combination of guideRNA with SpCas9 can effectively delete the exonic fragment of the SLC25A38 gene in HEK293T cells.

ATP5F1A encodes part of the catalytic core of mitochondrial complex V, which is responsible for the majority of ATP production. Mitochondrial complex V deficiency, nuclear type 4A (MC5DN4A; MIM#620358) is due to monoallelic pathogenic variants in ATP5F1A. MC5DN4A is a neonatal-onset disorder with features including growth faltering, developmental delay, epilepsy, and a biochemical phenotype indicative of urea cycle dysfunction. Interestingly, patients who have MC5DN4A due to the recurrent pathogenic ATP5F1A c.620G>A (p.Arg207His) variant appear to demonstrate clinical resolution before 18 months of age. All reported cases of MC5DN4A due to the ATP5F1A c.620G>A (p.Arg207His) variant have been de novo. Here we present a mother and her three children with MC5DN4A harboring the ATP5F1A c.620G>A (p.Arg207His) variant. The oldest child has growth faltering, seizures, autism spectrum disorder, global developmental delay, urea cycle dysfunction, and elevated plasma lactate without full clinical resolution. The two younger children have similar biochemical findings with a more severe clinical phenotype including congenital heart disease, growth faltering, sideroblastic anemia, and hypogammaglobulinemia, however both children are showing signs of spontaneous clinical resolution. Additionally, both younger children have a deletion of the entire coding sequence of NDUFA12, which may be contributing to the more severe presentation. The mother is reportedly asymptomatic. In summary, we present the first known instance of transgenerational transmission of the pathogenic ATP5F1A c.620G>A (p.Arg207His) variant. The presence of congenital heart disease, sideroblastic anemia, and hypogammaglobulinemia in two cases may indicate a phenotypic expansion of MC5DN4A or may suggest a modifying effect of the NDUFA12 deletion on the phenotype.

Erythropoietin-stimulating agent-resistant anemia (ESA-RA) is observed in a significant number of hemodialysis (HD) patients. However, the underlying mechanisms remain unclear. We report two HD patients in whom vitamin B6 (VB6) deficiency was thought to be the cause of ESA-RA, and oral administration of pyridoxal phosphate hydrate led to prompt elevation of hemoglobin levels. VB6 is crucial for heme biosynthesis. HD removes VB6 from the serum. Therefore, patients undergoing HD are theoretically prone to VB6 deficiency anemia. However, reports of VB6 deficiency anemia in HD patients are scarce, and we speculate that this is an under-recognized cause of ESA-RA.

TRNT1 deficiency (SIFD syndrome) is a rare inborn error of immunity characterized by sideroblastic anemia, immunodeficiency, periodic fevers, and developmental delay. We report two Romanian patients with genetically confirmed TRNT1 deficiency presenting with characteristic hematologic and immunologic abnormalities and a distinctive facial dysmorphism. One patient additionally developed severe gastrointestinal ischemia and intracranial hemorrhage in the setting of concomitant hereditary antithrombin III deficiency. These observations expand the phenotypic spectrum associated with TRNT1 deficiency and highlight the marked clinical variability of this disorder. The contribution of TRNT1-associated inflammation to the vascular phenotype remains speculative and cannot be distinguished from the effects of the concomitant thrombophilic condition.

Microcytic hypochromic anemia is commonly presumed to represent iron deficiency anemia (IDA) at initial presentation. However, failure to respond to iron supplementation and iron indices inconsistent with IDA should prompt early diagnostic reassessment. We report a 67-year-old woman with severe microcytic hypochromic anemia after ineffective iron therapy. Iron studies indicated iron loading with impaired iron utilization rather than iron deficiency. Bone marrow Perls staining revealed ring sideroblasts in 14% of erythroblasts. Further stratified evaluation supported an acquired ring sideroblast phenotype, but the etiology could not be conclusively established. The patient received multifactorial supportive management, including discontinuation of unnecessary iron supplementation, early transfusion support, erythropoietin during hospitalization, pyridoxine supplementation, infection treatment, and optimization of comorbidities. Hemoglobin gradually improved and remained stable during follow-up without further transfusion. This case underscores the importance of early reassessment in older patients with iron-refractory microcytic anemia and discordant iron indices. Bone marrow Perls staining is critical for identifying ring sideroblasts. Assessment including SF3B1 testing may aid etiologic stratification, but SF3B1 negativity alone is insufficient to exclude clonal myeloid disease.

Transfusion-dependent anemia (TDA) in children is often attributed to hemoglobinopathies; however, a spectrum of non-hemoglobinopathy disorders can also lead to transfusion dependence, complicating diagnosis and management. In this article, we share our experience with such non-hemoglobinopathy causes of TDA. A retrospective chart review was conducted over five years (2018-2023) at a tertiary pediatric hematology center. Among 93 children identified with TDA, 80 had hemoglobinopathies, while 13 had alternative diagnoses. These included immune-mediated hematological disorders, marrow failure syndromes, congenital RBC/platelet defects, and systemic illnesses. Descriptive statistics summarized clinical and demographic data. Of the 93 children with TDA, 13 had non-hemoglobinopathy causes: immune-mediated disorders (AIHA, Evans syndrome, PRCA, n = 4), marrow failure syndromes (sideroblastic anemia, dyskeratosis congenita, n = 3), inherited red cell/platelet defects (G6PD deficiency, Glanzmann thrombasthenia, n = 3), and systemic illnesses (vasculitis, Langerhans cell histiocytosis, hypereosinophilic syndrome, n = 3). The mean age was 4 years 5 months, with a male-to-female ratio of 1.16:1. Hepatosplenomegaly was observed in 8/13 cases. Non-hemoglobinopathy causes of TDA are heterogeneous, encompassing systemic, immune, genetic, and marrow failure disorders. Structured diagnostic evaluation is critical to distinguish them from hemoglobinopathies, enabling accurate treatment and improved outcomes.