Megaloblastic anemia is a type of macrocytic anemia. An anemia is a red blood cell defect that can lead to an undersupply of oxygen. Megaloblastic anemia results from inhibition of DNA synthesis during red blood cell production. When DNA synthesis is impaired, the cell cycle cannot progress from the G2 growth stage to the mitosis (M) stage. This leads to continuing cell growth without division, which presents as macrocytosis. Megaloblastic anemia has a rather slow onset, especially when compared to that of other anemias. The defect in red cell DNA synthesis is most often due to hypovitaminosis, specifically vitamin B12 deficiency or folate deficiency. Loss of micronutrients may also be a cause.
Diamond–Blackfan anemia (DBA) is a congenital erythroid aplasia that usually presents in infancy. DBA causes low red blood cell counts (anemia), without substantially affecting the other blood components, which are usually normal. This is in contrast to Shwachman–Bodian–Diamond syndrome, in which the bone marrow defect results primarily in neutropenia, and Fanconi anemia, where all cell lines are affected resulting in pancytopenia. There is a risk to develop acute myelogenous leukemia (AML) and certain other cancers.
GATA-binding factor 1 or GATA-1 is the founding member of the GATA family of transcription factors. This protein is widely expressed throughout vertebrate species. In humans and mice, it is encoded by the GATA1 and Gata1 genes, respectively. These genes are located on the X chromosome in both species.
Pendrin is an anion exchange protein that in humans is encoded by the SLC26A4 gene . Pendrin was initially identified as a sodium-independent chloride-iodide exchanger with subsequent studies showing that it also accepts formate and bicarbonate as substrates. Pendrin is similar to the Band 3 transport protein found in red blood cells. Pendrin is the protein which is mutated in Pendred syndrome, which is an autosomal recessive disorder characterized by sensorineural hearing loss, goiter and a partial organification problem detectable by a positive perchlorate test.
Thiamine transporter 2 (ThTr-2), also known as solute carrier family 19 member 3, is a protein that in humans is encoded by the SLC19A3 gene. SLC19A3 is a thiamine transporter.
Folate transporter 1 is a protein which in humans is encoded by the SLC19A1 gene.
The major facilitator superfamily (MFS) is a superfamily of membrane transport proteins that facilitate movement of small solutes across cell membranes in response to chemiosmotic gradients.
Fanconi anemia group C protein is a protein that in humans is encoded by the FANCC gene. This protein delays the onset of apoptosis and promotes homologous recombination repair of damaged DNA. Mutations in this gene result in Fanconi anemia, a human rare disorder characterized by cancer susceptibility and cellular sensitivity to DNA crosslinks and other damages.
Fanconi anaemia, complementation group A, also known as FAA, FACA and FANCA, is a protein which in humans is encoded by the FANCA gene. It belongs to the Fanconi anaemia complementation group (FANC) family of genes of which 12 complementation groups are currently recognized and is hypothesised to operate as a post-replication repair or a cell cycle checkpoint. FANCA proteins are involved in inter-strand DNA cross-link repair and in the maintenance of normal chromosome stability that regulates the differentiation of haematopoietic stem cells into mature blood cells.
Methionine synthase reductase, also known as MSR, is an enzyme that in humans is encoded by the MTRR gene.
MTHFD1 is a gene located in humans on chromosome 14 that encodes for a protein with three distinct enzymatic activities. C-1-tetrahydrofolate synthase, cytoplasmic also known as C1-THF synthase is an enzyme that in humans is encoded by the MTHFD1 gene.
Fanconi anemia group F protein is a protein that in humans is encoded by the FANCF gene.
Thiamin pyrophosphokinase 1 is an enzyme that in humans is encoded by the TPK1 gene.
Hereditary folate malabsorption (HFM) is a rare autosomal recessive disorder caused by loss-of-function mutations in the proton-coupled folate transporter (PCFT) gene, resulting in systemic folate deficiency and impaired delivery of folate to the brain.
The proton-coupled folate transporter is a protein that in humans is encoded by the SLC46A1 gene. The major physiological roles of PCFTs are in mediating the intestinal absorption of folate, and its delivery to the central nervous system.
The Reduced Folate Carrier (RFC) Family is a group of transport proteins that is part of the major facilitator superfamily. RFCs take up folate, reduced folate, derivatives of reduced folate and the drug, methotrexate.
Thiamine responsive megaloblastic anemia syndrome is a very rare autosomal recessive genetic disorder affecting a thiamine transporter, which is characterized by megaloblastic anemia, diabetes mellitus, and hearing loss. The condition is treated with high doses of thiamine.
The mitochondrial folate transporter (MTF) is a transport protein that facilitates the transfer of tetrahydrofolate across the inner mitochondrial membrane. It is encoded by the SLC25A32 gene and belongs to the mitochondrial carrier superfamily.
A heme transporter is a protein that delivers heme to the various parts of a biological cell that require it.
Biotin-thiamine-responsive basal ganglia disease (BTBGD) is a rare disease that affects the nervous system, particularly the basal ganglia in the brain. It is a treatable neurometabolic disorder with autosomal recessive inheritance. First described in 1998 and then genetically distinguished in 2005, the disease is characterized by progressive brain damage that, if left untreated, can lead to coma and/or death. Commonly observed in individuals with BTBGD is recurring subacute encephalopathy along with confusion, seizures, and disordered movement (hypokinesia).
