Search

Background: Imerslund-Gräsbeck syndrome (IGS) is an autosomal recessive disorder characterized by selective vitamin B12 malabsorption, resulting in vitamin B12 deficiency and impaired reabsorption of proximal tubular proteins.This case highlights a previously unidentified compound heterozygous variant in the Amnionless (AMN) gene that causes IGS syndrome and underscores the importance of long-term oral vitamin B12 replacement therapy in managing the condition., Case Presentation: In this retrospective analysis, we present the clinical data of a 3-year and 6-month-old female child diagnosed with IGS at Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, China, in November 2018. The child was admitted to the hospital due to a history of anemia persisting for over a month. There was no previous significant medical history. The admission examination revealed megaloblastic anemia with proteinuria. Serum vitamin B12 levels were decreased, while folic acid and renal function were normal. The patient was diagnosed with megaloblastic anemia and started long-term oral vitamin B12 replacement therapy. Throughout the follow-up period, blood tests consistently showed normal results, while proteinuria persisted. In November 2019, the child and her parents underwent whole exome sequencing analysis, which revealed a novel compound heterozygous variant in the AMN gene: c.162 + 1G > A and c.922 C > T (p.Q308X) in the child, c.162 + 1G > A in the father, and c.922 C > T (p.Q308X) in the mother. Therefore, this child was further diagnosed with IGS., Conclusions: In this case, whole exome sequencing proves to be highly practical in daily healthcare for diagnosing and refining rare or ultra-rare diseases with ambiguous phenotypes or genetic diversity. It is also valuable for prognostic evaluation and personalized management. Additionally, the oral vitamin B12 treatment demonstrated positive clinical effects for the child, offering a new option for patients unable to undergo intramuscular vitamin B12 replacement therapy., (© 2024. The Author(s).)

Background: Individuals with thiamine-responsive megaloblastic anemia (TRMA) mainly manifest macrocytic anemia, sensorineural deafness, ocular complications, and nonautoimmune diabetes. Macrocytic anemia and diabetes may be responsive to high-dosage thiamine treatment, in contrast to sensorineural deafness. Little is known about the efficacy of thiamine treatment on ocular manifestations., Cases Presentation: Our objective is to report data from four Italian TRMA patients: in Cases 1, 2 and 3, the diagnosis of TRMA was made at 9, 14 and 27 months. In 3 out of 4 subjects, thiamine therapy allowed both normalization of hyperglycemia, with consequent insulin suspension, and macrocytic anemia. In all Cases, thiamine therapy did not resolve the clinical manifestation of deafness. In Cases 2 and 3, follow-up showed no blindness, unlike Case 4, in which treatment was started for megaloblastic anemia at age 7 but was increased to high doses only at age 25, when the genetic diagnosis of TRMA was performed., Conclusions: Early institution of high-dose thiamine supplementation seems to prevent the development of retinal changes and optic atrophy in TRMA patients. The spectrum of clinical manifestations is broad, and it is important to describe known Cases to gain a better understanding of this rare disease., (© 2023. The Author(s).)

Background: In ineffective erythropoiesis, hepcidin synthesis is suppressed by erythroid regulators, namely erythroferrone and growth differentiation factor-15. For the first time, the hypothesis that iron overload in megaloblastic anemia may be related to ineffective erythropoiesis is explored by describing the kinetics of hepcidin, erythroferrone, and growth differentiation factor-15 levels in a patient diagnosed with megaloblastic anemia associated with iron overload., Case Presentation: An 81-year-old Caucasian male was admitted for fatigue. He had type-2 diabetes previously treated with metformin, ischemic cardiac insufficiency, and stage-3 chronic kidney disease. Vitiligo was observed on both hands. Biological tests revealed normocytic non-regenerative anemia associated with hemolysis, thrombocytopenia, and elevated sideremia, ferritin, and transferrin saturation levels. Megaloblastic anemia was confirmed with undetectable blood vitamin B12 and typical cytological findings like hyper-segmented neutrophils in blood and megaloblasts in bone marrow. The patient received vitamin B12 supplementation. At 3 months, biological parameters reached normal values. Hepcidin kinetics from diagnosis to 3 months inversely correlated with those of erythroferrone and growth differentiation factor-15., Conclusions: This case suggests that iron-overload mechanisms of dyserythropoietic anemias may apply to megaloblastic anemias., (© 2021. The Author(s).)

Background: Thiamine-responsive megaloblastic anemia (TRMA) is a rare autosomal recessive inherited disease characterized by the clinical triad of megaloblastic anemia, sensorineural deafness, and diabetes mellitus. To date, only 100 cases of TRMA have been reported in the world., Case Presentation: Here, we describe a six-year-old boy with diabetes mellitus, anemia, and deafness. Additionally, he presented with thrombocytopenia, leukopenia, horizontal nystagmus, hepatomegaly, short stature, ventricular premature beat (VPB), and cerebral infarction. DNA sequencing revealed a novel compound heterozygous mutation in the SLC19A2 gene: (1) a duplication c.405dupA, p.Ala136Serfs*3 (heterozygous) and (2) a nucleotide deletion c.903delG p.Trp301Cysfs*13 (heterozygous). The patient was diagnosed with a typical TRMA., Conclusion: Novel mutations in the SLC19A2 gene have been identified, expanding the mutation spectrum of the SLC19A2 gene. For the first time, VPB and cerebral infarction have been identified in patients with TRMA syndrome, providing a new understanding of the phenotype.

Introduction: Although vitamin B12 deficiency is a well-known cause of hematological and neuropsychiatric illness, the presentation of combined severe pancytopenia, demyelination and prominent psychiatric impairment is rare., Case Presentation: We present a case of a previously healthy 55-year-old East African man with severe vitamin B12 deficiency (serum vitamin B12 22pmol/L) secondary to pernicious anemia. He had a severe hypoproliferative megaloblastic anemia with hemolysis (hemoglobin 61g/L, mean corpuscular volume 99fL, reticulocytes 0.8%, haptoglobin undetectable), leukopenia (2.7×109/L), thrombocytopenia (96×109/L), ataxia with central demyelination, and megaloblastic madness. The patient's anemia, myelopathy and psychiatric condition responded well to parenteral vitamin B12 replacement therapy, with significant improvement seen within weeks., Conclusion: Hematological manifestations of vitamin B12 deficiency are typically inversely correlated with the presence and severity of neuropsychiatric impairment. Although uncommon, a presentation with severe hematological and neuropsychiatric disease can occur, as illustrated by this case. Its presence may help guide diagnosis as well as provide clinically important prognostic information.

Background: Thiamine diphosphate (ThDP) is the active form of thiamine, and it serves as a cofactor for several enzymes, both cytosolic and mitochondrial. Isolated mitochondria have been shown to take up thiamine yet thiamine diphosphokinase is cytosolic and not present in mitochondria. Previous reports indicate that ThDP can also be taken up by rat mitochondria, but the kinetic constants associated with such uptake seemed not to be physiologically relevant., Results: Here we examine ThDP uptake by mitochondria from several human cell types, including cells from patients with thiamine-responsive megaloblastic anemia (TRMA) that lack a functional thiamine transporter of the plasma membrane. Although mitochondria from normal lymphoblasts took up thiamine in the low micromolar range, surprisingly mitochondria from TRMA lymphoblasts lacked this uptake component. ThDP was taken up efficiently by mitochondria isolated from either normal or TRMA lymphoblasts. Uptake was saturable and biphasic with a high affinity component characterized by a Km of 0.4 to 0.6 microM. Mitochondria from other cell types possessed a similar high affinity uptake component with variation seen in uptake capacity as revealed by differences in Vmax values., Conclusions: The results suggest a shared thiamine transporter for mitochondria and the plasma membrane. Additionally, a high affinity component of ThDP uptake by mitochondria was identified with the apparent affinity constant less than the estimates of the cytosolic concentration of free ThDP. This finding indicates that the high affinity uptake is physiologically significant and may represent the main mechanism for supplying phosphorylated thiamine for mitochondrial enzymes.